0:00:17 > 0:00:23In this episode, we'll explore an extraordinary relationship...
0:00:23 > 0:00:26HE SPEAKS PORTUGUESE
0:00:26 > 0:00:31..reveal prehistoric creatures that could come back from the dead
0:00:31 > 0:00:36and find out why Spain is under attack from space balls.
0:00:36 > 0:00:40It could be capable to destroy a house.
0:00:43 > 0:00:47But first to America, and to the coast of California,
0:00:47 > 0:00:52where, in February 2016, a gourmet restaurant became famous
0:00:52 > 0:00:54for a very unexpected guest.
0:00:55 > 0:00:58I came in, and yes, she was there,
0:00:58 > 0:01:03in booth number 65, which is the best table in the restaurant,
0:01:03 > 0:01:04right on the water.
0:01:07 > 0:01:12To Chef Bernard's surprise, a tiny sea lion pup was sitting,
0:01:12 > 0:01:14waiting for service.
0:01:14 > 0:01:17I've been here for 21 years and I've never seen something like this.
0:01:22 > 0:01:24He named her Marina.
0:01:24 > 0:01:27And stranger still, she wasn't a one-off.
0:01:30 > 0:01:34This sea lion pup turned up on the streets of San Francisco.
0:01:34 > 0:01:37Another was found in a toilet.
0:01:37 > 0:01:41Whilst this one was caught on CCTV indulging in a spot of shopping.
0:01:45 > 0:01:50Up and down the coast, lots of these animals were giving up on the ocean
0:01:50 > 0:01:52and moving inland.
0:01:52 > 0:01:54Strange behaviour indeed.
0:01:56 > 0:01:59And sea lions weren't the only animals behaving oddly
0:01:59 > 0:02:01on the California coast.
0:02:01 > 0:02:03Check this out.
0:02:03 > 0:02:07During 2015 and 16, millions of pelagic red crabs washed up
0:02:07 > 0:02:09like a crimson tide.
0:02:13 > 0:02:14And deadly venomous sea snakes
0:02:14 > 0:02:17that are usually only found in the tropics
0:02:17 > 0:02:19littered the state's beaches.
0:02:23 > 0:02:28But why were these marine creatures suddenly turning terrestrial?
0:02:30 > 0:02:35Well, Chef Bernard's uninvited guest could give us a clue.
0:02:35 > 0:02:40By seeking out a seafood restaurant, Marina was smarter than the other
0:02:40 > 0:02:44sea lion pups because they all had one thing in common...
0:02:46 > 0:02:48..protruding ribs,
0:02:48 > 0:02:50glassy eyes.
0:02:50 > 0:02:52These pups were starving.
0:02:55 > 0:03:00Marina was just one of over 6,500 skinny pups
0:03:00 > 0:03:03rescued across the state.
0:03:03 > 0:03:05The pups that are coming in are extremely emaciated.
0:03:05 > 0:03:08A lot of our pups come into us about six months old,
0:03:08 > 0:03:11and they're coming in just barely over birth weight.
0:03:16 > 0:03:21What was causing these starving pups to come ashore in their thousands?
0:03:24 > 0:03:29Well, there's one last unexpected piece to this puzzle.
0:03:29 > 0:03:31Just a week before Marina showed up
0:03:31 > 0:03:34at Chef Bernard's restaurant, something
0:03:34 > 0:03:38truly extraordinary made a sudden appearance
0:03:38 > 0:03:40just 15km down the coast.
0:03:42 > 0:03:45Wow! Look at that.
0:03:45 > 0:03:49As the tide falls back along the beach in Coronado,
0:03:49 > 0:03:51a piece of the past is unveiled.
0:03:51 > 0:03:56You're looking at the remains of the 300-foot long SS Monte Carlo.
0:03:58 > 0:04:03But the SS Monte Carlo sank back in 1937.
0:04:03 > 0:04:05So where had this wreck suddenly appeared from?
0:04:07 > 0:04:10And how can it explain the sea snakes,
0:04:10 > 0:04:13crab invasion and sea lions starving to death?
0:04:19 > 0:04:22Well, all these bizarre events
0:04:22 > 0:04:27were just symptoms of something much bigger and much stranger.
0:04:31 > 0:04:362015-'16 was what's known as an El Nino Year -
0:04:36 > 0:04:40a global weather event powerful enough to affect the whole planet.
0:04:45 > 0:04:49Normally, trade winds in the Pacific blow from east to west,
0:04:49 > 0:04:54dragging warm surface waters towards Indonesia and Northeast Australia.
0:04:55 > 0:05:00Meanwhile, deeper colder waters in the east rise to the surface.
0:05:00 > 0:05:05But every few years, the trade winds weaken and can't change,
0:05:05 > 0:05:08bringing in warmer water to the West Coast of America.
0:05:13 > 0:05:16And it's these unusually warm waters
0:05:16 > 0:05:20caused by El Nino that explain our Californian conundrum.
0:05:22 > 0:05:24They triggered severe storms
0:05:24 > 0:05:28that washed away tonnes of sand and exposed
0:05:28 > 0:05:31the long-lost wreck of the SS Monte Carlo.
0:05:32 > 0:05:37And warm currents brought sea snakes and red crabs up from the tropics.
0:05:39 > 0:05:44But why would a hotter ocean spell starvation for Marina and thousands
0:05:44 > 0:05:46of other sea lions?
0:05:48 > 0:05:51Well, there's still plenty of fish out there,
0:05:51 > 0:05:54but not in the right place.
0:05:54 > 0:05:55It shifted into the cooler waters,
0:05:55 > 0:05:57further down below or further offshore,
0:05:57 > 0:06:01and that's what El Nino does. El Nino brings in this really warm
0:06:01 > 0:06:03water current, and so, their cold-water prey
0:06:03 > 0:06:05move with the cold water.
0:06:06 > 0:06:09Adult sea lions can follow the fish offshore,
0:06:09 > 0:06:11but breeding mothers and pups can't.
0:06:13 > 0:06:16Many perished, but the lucky ones were rescued.
0:06:18 > 0:06:21And Chef Bernard waved a fond farewell
0:06:21 > 0:06:23when Marina returned to the wild.
0:06:23 > 0:06:27Whoo! She really, really regained a lot of weight,
0:06:27 > 0:06:29so she went from 20lb, became 40, 45lb.
0:06:29 > 0:06:31So she was healthy, she was happy,
0:06:31 > 0:06:35she was sassy and she was like, "Hey, Chef Bernard,
0:06:35 > 0:06:38"time to go back in the big great blue!" And that's what we did.
0:06:52 > 0:06:57So, a sea lion sauntering into a seafood restaurant was just a small,
0:06:57 > 0:07:01skinny symptom of the world's largest weather phenomenon.
0:07:01 > 0:07:06And the 2015-2016 El Nino was no ordinary El Nino.
0:07:06 > 0:07:12It was the strongest since the 1950s and its effects were felt far wider
0:07:12 > 0:07:14than the Sunshine State.
0:07:14 > 0:07:18Yes, this was some seriously weird weather.
0:07:21 > 0:07:25Yes, whilst strange weather was to blame for the peculiar events in
0:07:25 > 0:07:32California, our next mystery was washed up by unusual currents
0:07:32 > 0:07:33off Brazil.
0:07:37 > 0:07:42Every June, 71-year-old Joao Pereira waits for his best friend,
0:07:42 > 0:07:44Dindim, to arrive.
0:07:44 > 0:07:47HE SPEAKS PORTUGUESE
0:07:49 > 0:07:51They haven't seen each other for months,
0:07:51 > 0:07:54because Dindim's been away at sea.
0:07:54 > 0:07:56But finally, the wait is over.
0:08:03 > 0:08:05Sorry, I didn't tell you, did I?
0:08:05 > 0:08:06Dindim's a penguin.
0:08:09 > 0:08:12A Magellanic penguin, to be precise.
0:08:12 > 0:08:14And for the past five years,
0:08:14 > 0:08:17Dindim and Joao have been devoted to each other.
0:08:17 > 0:08:22So how did man and bird become such bosom buddies?
0:08:25 > 0:08:30Joao's house backs onto Proveta Beach, near Rio De Janeiro.
0:08:31 > 0:08:34In May 2011, he found Dindim on the sand,
0:08:34 > 0:08:37barely moving and covered in oil.
0:08:39 > 0:08:40Joao looked after the penguin.
0:08:43 > 0:08:44He cleaned his feathers.
0:08:48 > 0:08:50And fed him sardines.
0:08:53 > 0:08:54After a few days,
0:08:54 > 0:08:57when he thought Dindim was strong enough to fend for himself,
0:08:57 > 0:09:00Joao took the penguin to a nearby island
0:09:00 > 0:09:01and released him into the sea.
0:09:06 > 0:09:11But just a few hours later, Joao heard squeaking in his backyard.
0:09:12 > 0:09:16Much to his surprise, the penguin was back,
0:09:16 > 0:09:19and made himself at home with Joao and his wife.
0:09:35 > 0:09:39Dindim and Joao were inseparable for 11 months.
0:09:39 > 0:09:42But then the penguin suddenly left.
0:09:43 > 0:09:47Perhaps his instincts had kicked in and he'd gone to find his own kind.
0:09:53 > 0:09:57Magellanic penguins live in the sea off of South America,
0:09:57 > 0:10:01and sometimes they'll venture as far north as Rio here.
0:10:01 > 0:10:05But once a year they have to head back south to Patagonia to breed.
0:10:05 > 0:10:09So Joao could only imagine that Dindim, fully restored to health,
0:10:09 > 0:10:11had hopped down off of the sofa,
0:10:11 > 0:10:14taken to the sea and swum south to be reunited with
0:10:14 > 0:10:16some of his fellow penguins.
0:10:20 > 0:10:22But what's incredible
0:10:22 > 0:10:25is that a few months later, much to Joao's delight,
0:10:25 > 0:10:27Dindim returned.
0:10:27 > 0:10:31HE SPEAKS PORTUGUESE
0:10:33 > 0:10:36And the same thing happens every year.
0:10:37 > 0:10:40Dindim heads out to sea for a few months to feed,
0:10:40 > 0:10:43but he always returns to Joao.
0:10:43 > 0:10:45So what's going on?
0:10:45 > 0:10:48Why does Dindim keep coming back to Joao
0:10:48 > 0:10:51rather than living with his own species?
0:10:53 > 0:10:57Well, the answer may lie in the fact that the penguin was only about
0:10:57 > 0:10:59a year old when Joao rescued him.
0:11:01 > 0:11:05It could be that Dindim has imprinted upon Joao
0:11:05 > 0:11:09to the extent that he sees Joao as his parent.
0:11:09 > 0:11:11You see, when birds hatch,
0:11:11 > 0:11:13they do so with little sense of identity.
0:11:13 > 0:11:18They have to look around them to see what they are and how to behave.
0:11:18 > 0:11:23And sometimes, if the first thing they see is a human,
0:11:23 > 0:11:25they bond to it for life.
0:11:28 > 0:11:32So perhaps this special relationship is due to some kind of
0:11:32 > 0:11:35delayed imprinting. A case of mistaken identity.
0:11:38 > 0:11:43But there could be another possibility that Dindim sees Joao
0:11:43 > 0:11:46not as a parent, but as his partner.
0:11:48 > 0:11:52You see, Dindim always returns around July,
0:11:52 > 0:11:56which is the beginning of the penguin breeding season.
0:11:56 > 0:11:59Other Magellanic penguins are in Patagonia then,
0:11:59 > 0:12:01raising a family with their mate.
0:12:05 > 0:12:08So is Dindim's affectionate behaviour actually
0:12:08 > 0:12:09an attempt at courtship?
0:12:11 > 0:12:13Well, it's not quite that simple.
0:12:13 > 0:12:18Penguins are usually very loyal to the places that they spend their
0:12:18 > 0:12:19summer months.
0:12:22 > 0:12:24They breed in Patagonia,
0:12:24 > 0:12:28they usually come back to the very same beach every year and they nest
0:12:28 > 0:12:30in the very same hole every year with the same partner.
0:12:30 > 0:12:32Most of them are like that.
0:12:32 > 0:12:36Because Dindim spends so long with Mr Joao on Proveta Beach
0:12:36 > 0:12:39he probably imprinted and learned that
0:12:39 > 0:12:42that place is a safe place to be,
0:12:42 > 0:12:45and is the place he has to go during the summer months.
0:12:45 > 0:12:50So it seems that because Dindim spent his formative first summer
0:12:50 > 0:12:54with Joao, he now sees that beach as his home.
0:12:54 > 0:12:57Whatever the biological explanation may be,
0:12:57 > 0:12:59the warm fuzzy feeling between
0:12:59 > 0:13:02this penguin and his pal is clearly mutual.
0:13:02 > 0:13:06So Dindim is usually very calm and comfortable and happy around
0:13:06 > 0:13:08Mr Joao, and the opposite is true as well.
0:13:08 > 0:13:11He is in heaven when Dindim is around.
0:13:11 > 0:13:14I would say this is a friendship, why not?
0:13:14 > 0:13:18What better definition for friendship than that?
0:13:18 > 0:13:22Without Joao's help, Dindim surely would have died.
0:13:22 > 0:13:27His kind actions have earned him an unlikely new best friend.
0:13:36 > 0:13:40While Atlantic currents delivered this penguin to a loving new home,
0:13:40 > 0:13:44unusual weather revealed a puzzle in the permafrost.
0:13:47 > 0:13:53Siberia. Where temperatures often fall to minus-40 degrees.
0:13:53 > 0:13:56And the ground is frozen solid year round.
0:13:58 > 0:14:00But in August 2015,
0:14:00 > 0:14:05a freak flood in the Sakha Republic exposed a fresh patch of tundra.
0:14:07 > 0:14:08Scientists working in the area
0:14:08 > 0:14:10stumbled across a weird-looking lump.
0:14:22 > 0:14:25They chipped away at the block of ice...
0:14:25 > 0:14:28Something furry emerged.
0:14:28 > 0:14:31The scientists had uncovered two frozen animals,
0:14:31 > 0:14:33but what could they be?
0:14:37 > 0:14:38Wild dogs?
0:14:38 > 0:14:41Polar bears?
0:14:41 > 0:14:44No, this was something even more extraordinary.
0:14:46 > 0:14:49A couple of very young lion cubs.
0:14:54 > 0:14:55Wait a minute.
0:14:55 > 0:14:59Lions in Siberia, how could that be?
0:14:59 > 0:15:04I mean, we all know that lions roam the plains of Africa here.
0:15:04 > 0:15:09And that there is a small population over here in north-western India.
0:15:09 > 0:15:15But that's still more than 3,000 miles away from Siberia, here.
0:15:15 > 0:15:19So how did those cubs turn up so far from home?
0:15:21 > 0:15:26Well, in fact, the icy Siberian tundra was their home.
0:15:26 > 0:15:29But not for 10,000 years.
0:15:29 > 0:15:32These are baby cave lions, and they've been extinct for millennia.
0:15:35 > 0:15:40Cave lions were around from a little over 300,000 years ago,
0:15:40 > 0:15:42when we first find them in Europe.
0:15:42 > 0:15:45To approximately between 14,000 and 10,000 years ago
0:15:45 > 0:15:49was when they started to disappear from most of the range.
0:15:56 > 0:16:01Cave lions were about 10% bigger than modern African lions
0:16:01 > 0:16:03and roamed most of the Northern Hemisphere,
0:16:03 > 0:16:05from Alaska to eastern Russia.
0:16:07 > 0:16:09After detailed investigation,
0:16:09 > 0:16:12biologists hypothesise that the cub's mother
0:16:12 > 0:16:16left them in a den while she went off hunting.
0:16:16 > 0:16:18And then while she was away,
0:16:18 > 0:16:20a landslide caused the den to collapse,
0:16:20 > 0:16:22and the cubs perished.
0:16:25 > 0:16:29But if these cubs have been dead for over 10,000 years,
0:16:29 > 0:16:32how do they look so good for their age?
0:16:33 > 0:16:37Well, a simple demonstration should make that clear.
0:16:37 > 0:16:39But I warn you, it's not pretty.
0:16:39 > 0:16:40Look away if you're squeamish.
0:16:43 > 0:16:45Left alone at room temperature,
0:16:45 > 0:16:48a chicken decomposes within a week or so.
0:16:48 > 0:16:51Bacteria and maggots make short work of the carcass.
0:16:53 > 0:16:57But if we simulate the Siberian permafrost,
0:16:57 > 0:16:59the chicken is frozen in time.
0:17:00 > 0:17:02It's not just icy temperatures
0:17:02 > 0:17:05that keep the flesh nice and fresh, though.
0:17:07 > 0:17:10A combination of a lack of oxygen and no sunlight
0:17:10 > 0:17:14also meant the cubs were preserved for thousands of years.
0:17:14 > 0:17:18A chance in a million for biologists.
0:17:18 > 0:17:21From a paleontological standpoint, it's a hugely significant find.
0:17:21 > 0:17:25We very rarely get soft tissue preservation of extinct animals.
0:17:25 > 0:17:28Not just the skeleton, but all the soft tissue, you know,
0:17:28 > 0:17:32all the muscles and the brain and the fur.
0:17:32 > 0:17:34It's just amazing.
0:17:36 > 0:17:41And the soft tissue is the final twist in this Siberian story.
0:17:41 > 0:17:44You see, not content with merely uncovering these cubs,
0:17:44 > 0:17:48biologists plan to do the unthinkable.
0:17:50 > 0:17:52To clone the cave lion.
0:17:53 > 0:17:56To bring it back to life.
0:17:56 > 0:17:58But how?
0:17:58 > 0:18:02Well, science has progressed a lot since the first mammal was cloned
0:18:02 > 0:18:04back in 1996.
0:18:06 > 0:18:09'Scientists in Scotland have produced the first-ever clone
0:18:09 > 0:18:10'of an adult animal.
0:18:13 > 0:18:14'Dolly, a seven-month-old sheep,
0:18:14 > 0:18:18'was created in a laboratory using a cell from another sheep.
0:18:18 > 0:18:21'The new step involves taking a cell from an adult sheep
0:18:21 > 0:18:24'and removing the genetic material from it.
0:18:24 > 0:18:28'The genes are then inserted into an empty egg cell taken from another
0:18:28 > 0:18:31'sheep. The egg is then used to start a pregnancy,
0:18:31 > 0:18:33'the offspring being a clone.'
0:18:38 > 0:18:43If intact DNA could be extracted from the cave lions then, in theory,
0:18:43 > 0:18:46they could be brought back from extinction.
0:18:48 > 0:18:52Korean biologist Hwang Woo-suk is taking tissue samples from the cubs.
0:19:07 > 0:19:11Russian and Korean scientists are already working on cloning
0:19:11 > 0:19:13ancient mammoths.
0:19:13 > 0:19:17And as far fetched as this Jurassic dream sounds,
0:19:17 > 0:19:19it might just be possible.
0:19:20 > 0:19:24You see, they don't need pristine DNA to try and bring back
0:19:24 > 0:19:28the cave lion, or, in this case, the mammoth.
0:19:28 > 0:19:32Let's imagine that these parts of this jigsaw represents the good
0:19:32 > 0:19:34mammoth DNA that they have.
0:19:34 > 0:19:38The problem is...they've only got half a mammoth.
0:19:38 > 0:19:43But their plan is to combine it with modern-day elephant DNA,
0:19:43 > 0:19:48and what they end up with is a sort of hybrid embryo,
0:19:48 > 0:19:51not an exact mammoth clone, but, perhaps,
0:19:51 > 0:19:53something pretty close to it.
0:19:55 > 0:19:58Even if scientists manage to create a viable embryo,
0:19:58 > 0:20:00that's just the first step.
0:20:02 > 0:20:04I think what people forget with cloning is that
0:20:04 > 0:20:06you need a host animal.
0:20:06 > 0:20:09And you need many, many replicates in order to get any sort of success.
0:20:09 > 0:20:13So dozens, to potentially hundreds, of surrogate mothers.
0:20:13 > 0:20:15Of course, if you look at modern lion populations,
0:20:15 > 0:20:18they are plummeting. Just in the last few decades,
0:20:18 > 0:20:21the lion populations have been cut almost in half.
0:20:21 > 0:20:25So the amount of resources that would go into cloning the cave lion,
0:20:25 > 0:20:28I think, could be much better spent on saving the lions
0:20:28 > 0:20:30that are around today.
0:20:33 > 0:20:37The possibility of cloning animals like cave lions and mammoths is
0:20:37 > 0:20:39undeniably exciting.
0:20:39 > 0:20:42But it's my duty to tell you that, at the moment,
0:20:42 > 0:20:45a real-life Jurassic Park is still some way off.
0:20:50 > 0:20:53We now travel to Florida,
0:20:53 > 0:20:56where intruders are lurking in the undergrowth.
0:20:58 > 0:21:00Miami.
0:21:00 > 0:21:02Glamorous. Cool.
0:21:02 > 0:21:05Playground of the rich and beautiful.
0:21:06 > 0:21:10But a recent invasion is distressing local residents.
0:21:12 > 0:21:15Oh, my God. I will never go out.
0:21:15 > 0:21:17I will not let my kids go outside and play.
0:21:18 > 0:21:21We didn't know what they were in the beginning.
0:21:21 > 0:21:24They would start climbing up the trees and just seemed to stay there.
0:21:24 > 0:21:26We began to see...hundreds.
0:21:27 > 0:21:31Properties are being overrun by alien creatures.
0:21:31 > 0:21:33I found one the size of my hand.
0:21:33 > 0:21:36So what's the cause of all of this anxiety?
0:21:37 > 0:21:39They are big. There are slimy
0:21:39 > 0:21:43and a lot of people think they're downright disgusting.
0:21:43 > 0:21:44Snails.
0:21:44 > 0:21:45Large snails.
0:21:45 > 0:21:46They're everywhere.
0:21:48 > 0:21:49I know what you're thinking,
0:21:49 > 0:21:52have the residents of Miami gone completely crazy?
0:21:52 > 0:21:56I mean, every garden has slugs and snails, doesn't it?
0:21:56 > 0:22:00Well, it might. But not snails like this one.
0:22:00 > 0:22:03You see, this is a giant African land snail.
0:22:03 > 0:22:05They can grow to up to 20 centimetres.
0:22:05 > 0:22:07They can live for up to nine years.
0:22:07 > 0:22:09These are monster snails.
0:22:12 > 0:22:14And they are causing panic because
0:22:14 > 0:22:17they don't just munch on a few garden plants.
0:22:19 > 0:22:22They'll eat over 500 different crops.
0:22:24 > 0:22:27They'll even devour people's homes.
0:22:29 > 0:22:31Yes, really.
0:22:31 > 0:22:32They're eating the concrete.
0:22:32 > 0:22:35Because they're getting calcium out of that to help build
0:22:35 > 0:22:37their shells stronger and bigger.
0:22:44 > 0:22:47But what's most worrying is that in Florida,
0:22:47 > 0:22:49they may carry a type of meningitis
0:22:49 > 0:22:54that can be passed on to humans via their slime.
0:22:54 > 0:22:59So these snails are a menace to human health and to the economy.
0:22:59 > 0:23:01But where have they all come from?
0:23:01 > 0:23:04Well, they are native to Africa.
0:23:04 > 0:23:08No-one is completely sure how they first came to Florida,
0:23:08 > 0:23:11but people have been caught smuggling them into the country.
0:23:14 > 0:23:16A lady coming back from Nigeria last year
0:23:16 > 0:23:18had 12 of them hidden under her dress.
0:23:18 > 0:23:20A man coming back from the Philippines,
0:23:20 > 0:23:24and he had one giant African snail in each one of his suit pockets.
0:23:24 > 0:23:26However they arrived,
0:23:26 > 0:23:30with plenty of lush vegetation and no natural predators,
0:23:30 > 0:23:33the invading snail population has boomed.
0:23:35 > 0:23:37Meet Harry the snail.
0:23:37 > 0:23:39Or maybe Harriet the snail,
0:23:39 > 0:23:42You see, it's difficult to ascribe a name to a snail,
0:23:42 > 0:23:43because they are hermaphrodite.
0:23:43 > 0:23:47They have both male and female reproductive apparatus.
0:23:47 > 0:23:49This is a real benefit to them.
0:23:49 > 0:23:52They don't have to go through that rigmarole of finding and then
0:23:52 > 0:23:56charming a mate. They can simply get on with reproduction.
0:23:56 > 0:24:01And they do. They can produce up to 1,000 eggs a year.
0:24:01 > 0:24:03I mean, you do the maths.
0:24:03 > 0:24:05These things are unstoppable.
0:24:07 > 0:24:11So the risk of disease and downright destruction
0:24:11 > 0:24:13means that local authorities are under pressure
0:24:13 > 0:24:16to eradicate these slimy intruders.
0:24:19 > 0:24:22We created a giant African land snail incident command.
0:24:24 > 0:24:28We're doing a lot of outreach in schools, at events,
0:24:28 > 0:24:29we do billboards,
0:24:29 > 0:24:31radio ads and television ads.
0:24:34 > 0:24:39The authorities rely on people ringing in with their sightings.
0:24:39 > 0:24:41I started seeing signs on the back of trucks which said,
0:24:41 > 0:24:43"Call the state of Florida."
0:24:43 > 0:24:45As soon as I saw this meningitis...
0:24:46 > 0:24:48..that scared me to death.
0:24:53 > 0:24:55They came several times a week,
0:24:55 > 0:24:58and they would pick up hundreds of them and put them in plastic bags.
0:24:58 > 0:25:00And, you know, take them away.
0:25:01 > 0:25:06The snail squad seem to be getting on top of the slow-mo swarm.
0:25:06 > 0:25:11We've collected over 162,000 giant African land snails.
0:25:11 > 0:25:14The idea is get the population down. And we've accomplished that.
0:25:14 > 0:25:18But if these snails can lay 100 eggs at a time,
0:25:18 > 0:25:20to get on top of the problem,
0:25:20 > 0:25:25the authorities are going to need to find every single last one of them.
0:25:26 > 0:25:31And until recently, that's been an almost impossible task.
0:25:31 > 0:25:35But now, the authorities have a secret weapon.
0:25:37 > 0:25:39Meet Sierra.
0:25:39 > 0:25:41Come on, let's go.
0:25:41 > 0:25:46We use canines because they can get to places where humans can't.
0:25:49 > 0:25:53They can smell that snail and go after it and alert us that there are
0:25:53 > 0:25:56giant African snails there.
0:25:56 > 0:25:57Yeah! Good girl, babe.
0:25:57 > 0:25:59You found it.
0:25:59 > 0:26:01Good girl.
0:26:01 > 0:26:02Good girl.
0:26:02 > 0:26:08In Shannon's garden, the snail squad's efforts seem to be working.
0:26:08 > 0:26:11It's been amazingly successful because for months,
0:26:11 > 0:26:13I have not seen a snail.
0:26:13 > 0:26:16But Mark and his team must remain vigilant.
0:26:18 > 0:26:22Just the other day we found a 4.8 incher, which is an adult,
0:26:22 > 0:26:26which means that there are children, or neonates
0:26:26 > 0:26:29that are out there in the wild. We have to keep looking for them.
0:26:35 > 0:26:37So the snail squad's efforts
0:26:37 > 0:26:40and their search for these marauding molluscs
0:26:40 > 0:26:42is set to continue.
0:26:42 > 0:26:46And Sierra's sniffing services are going to be needed for a while yet.
0:26:54 > 0:26:55Coming up...
0:26:55 > 0:26:57A strange glowing slime.
0:26:58 > 0:27:01And alien objects that fell from the sky.
0:27:04 > 0:27:09But first, we head to the holiday resort of Fethiye
0:27:09 > 0:27:12on the Turkish coast.
0:27:13 > 0:27:16On the 9th of July 2015,
0:27:16 > 0:27:19dive instructor Lutfu Tanriover jumped into the
0:27:19 > 0:27:22calm blue waters of the Mediterranean,
0:27:22 > 0:27:26something he'd done hundreds of times before.
0:27:26 > 0:27:30I have been diving the area for eight years.
0:27:30 > 0:27:33And at least once a week we are going to that dive site.
0:27:37 > 0:27:40Little did he know what he'd find under the waves this time.
0:27:45 > 0:27:49A blob of baffling proportions.
0:27:49 > 0:27:52It was three, four metres wide.
0:27:52 > 0:27:56And drifting about 22 metres in the middle of the water.
0:27:56 > 0:27:58It was a very, very big bubble.
0:28:02 > 0:28:06We were all fascinated by it because nobody had ever seen
0:28:06 > 0:28:08something like that before.
0:28:08 > 0:28:10I decided to call it The Thing.
0:28:11 > 0:28:15Lutfu posted this footage of The Thing online,
0:28:15 > 0:28:19where it grabbed the attention of marine biologist Steve Haddock.
0:28:21 > 0:28:24So what did he think this bewildering blob could be?
0:28:25 > 0:28:27When you see something like that,
0:28:27 > 0:28:30there's only a few things that it might potentially be.
0:28:30 > 0:28:32One of the things is a pyrosome.
0:28:37 > 0:28:40This is a colony of organisms that can form
0:28:40 > 0:28:43either a small tube or, actually, one species can form very,
0:28:43 > 0:28:47very large tubes that divers can actually swim inside of.
0:28:47 > 0:28:50But the thing that Lutfu filmed was a ball.
0:28:50 > 0:28:51Not a tube.
0:28:51 > 0:28:54So if it wasn't a colony of individual creatures,
0:28:54 > 0:28:57what was this awe-inspiring orb?
0:28:57 > 0:28:59And where had it come from?
0:29:01 > 0:29:05The secret to the blob's source lay inside the sphere.
0:29:05 > 0:29:08You see, initially, it looked translucent.
0:29:08 > 0:29:12See-through. But then, under closer inspection,
0:29:12 > 0:29:15Lutfu could see something inside.
0:29:19 > 0:29:22When you go next to it, we put the torches in it,
0:29:22 > 0:29:27and then we saw with the torches, we have seen so many particles in it.
0:29:29 > 0:29:32These particles provided a vital clue.
0:29:32 > 0:29:36You see, this isn't a single giant blob at all.
0:29:36 > 0:29:40But millions of tiny individual spheres.
0:29:40 > 0:29:42Squid eggs.
0:29:42 > 0:29:43Instead of having them individually,
0:29:43 > 0:29:46they're like little snacks for other organisms to live on,
0:29:46 > 0:29:50they embed them in a giant gelatinous mass.
0:29:50 > 0:29:55It's a strategy that certain species of squid use in the open ocean
0:29:55 > 0:29:58where there are lots of hungry mouths around.
0:29:58 > 0:30:01Predators could come from any direction,
0:30:01 > 0:30:03and you have very few ways to hide or secure your eggs.
0:30:03 > 0:30:05But if you put them in this mass,
0:30:05 > 0:30:07it's large enough, it excludes all the predators
0:30:07 > 0:30:09that are smaller than that.
0:30:13 > 0:30:18This enormous egg mass is the squid's way of maximising
0:30:18 > 0:30:20its offspring's chances of survival.
0:30:20 > 0:30:23Blobs like this are rarely seen,
0:30:23 > 0:30:26they last just a few days before breaking up.
0:30:26 > 0:30:30Then each baby squid will face the world alone.
0:30:33 > 0:30:35But there's one puzzle left.
0:30:36 > 0:30:42So how does a relatively small squid produce something so huge?
0:30:42 > 0:30:45Well, its eggs start off quite small.
0:30:45 > 0:30:50But they expand massively in sea water.
0:30:50 > 0:30:53It's a bit like frog spawn on steroids.
0:30:57 > 0:31:02So this vast blob of jelly is the secret to a squid's success.
0:31:02 > 0:31:05Protecting its precious eggs from predators.
0:31:09 > 0:31:12Whilst this bizarre ball appeared underwater...
0:31:13 > 0:31:16..our next mystery was spotted underground.
0:31:19 > 0:31:21In March 2016,
0:31:21 > 0:31:26Anthony Roberts was exploring this old slate mine in North Wales.
0:31:27 > 0:31:31Scoping out new areas for guided tours.
0:31:31 > 0:31:33His normal route in and out was flooded,
0:31:33 > 0:31:36so he used the emergency exit tunnels instead.
0:31:38 > 0:31:42On the way out, something stopped him in his tracks.
0:31:48 > 0:31:52A very strange, very bright luminous green material.
0:31:54 > 0:31:56It kept glowing.
0:32:02 > 0:32:07This glimmering stuff has been found in dark nooks and crannies
0:32:07 > 0:32:08around the globe.
0:32:11 > 0:32:12'Wow!'
0:32:12 > 0:32:14In Cornwall...
0:32:17 > 0:32:19Germany...
0:32:20 > 0:32:23- 'Holy- BLEEP, - look at that down there.
0:32:23 > 0:32:25'It is, it's glowing.'
0:32:25 > 0:32:27And even New York state.
0:32:28 > 0:32:32So what on earth could be producing this eerie green glow?
0:32:32 > 0:32:35Well, some rocks have the ability to fluoresce,
0:32:35 > 0:32:38the minerals within them can absorb light and then re-emit it.
0:32:38 > 0:32:41Like glow-in-the-dark stickers.
0:32:42 > 0:32:47True, but could this glowing green goo actually be alive?
0:32:50 > 0:32:54In Africa, there is a fungus that lights up the forest floor.
0:32:55 > 0:33:00It uses the luminous enzymes to breakdown leaf litter.
0:33:00 > 0:33:02The locals call it chimpanzee fire.
0:33:04 > 0:33:08But there was something completely unfathomable about the green goo
0:33:08 > 0:33:11that Anthony found in Wales.
0:33:11 > 0:33:16It had the disturbing ability to vanish before his eyes.
0:33:16 > 0:33:18It wasn't until I
0:33:18 > 0:33:21took a few steps closer,
0:33:21 > 0:33:24looked back at it from a slightly different direction and realised
0:33:24 > 0:33:27it's completely disappeared.
0:33:27 > 0:33:29I couldn't see it at all.
0:33:29 > 0:33:33So what was this glistening substance that glowed one moment
0:33:33 > 0:33:35and was gone the next?
0:33:37 > 0:33:42In the past, people believed it was the treasure of goblins.
0:33:42 > 0:33:44Probably hundreds of years,
0:33:44 > 0:33:47the stories about goblins hiding their gold in caves
0:33:47 > 0:33:49and all sorts of dark places.
0:33:52 > 0:33:56People walking past dark caves and such places see this glow of
0:33:56 > 0:33:59emeralds in the back and they go in and say,
0:33:59 > 0:34:02"This is the treasure, we're going to go in..."
0:34:02 > 0:34:04And you go in and grab a bit and you come out, and of course,
0:34:04 > 0:34:06it's not there. It's completely gone.
0:34:06 > 0:34:10So, obviously, it's goblins, what else could it be?
0:34:11 > 0:34:16In fact, these aren't sparkling gems hidden by mythical creatures.
0:34:16 > 0:34:19But the answer is almost as magical.
0:34:21 > 0:34:23It's a very clever trick by a moss
0:34:23 > 0:34:27that lives in these special circumstances.
0:34:27 > 0:34:29A moss called goblin gold.
0:34:29 > 0:34:32But this is no ordinary moss.
0:34:32 > 0:34:36It's developed some very special cells that allow it to live
0:34:36 > 0:34:39where there's almost no light.
0:34:39 > 0:34:41So how does it work?
0:34:44 > 0:34:46The front of each cell
0:34:46 > 0:34:47is curved like a lens,
0:34:47 > 0:34:51this focuses light rays and boosts the amount of light reaching the
0:34:51 > 0:34:55chloroplasts - those parts of the plant that produce energy
0:34:55 > 0:34:56through photosynthesis.
0:34:56 > 0:35:01The reason it glows is that some of the light is reflected back out
0:35:01 > 0:35:03through that lens.
0:35:03 > 0:35:07And this is the key to the moss's mysterious disappearance.
0:35:09 > 0:35:14Those reflected light rays can only be seen from one particular angle.
0:35:17 > 0:35:21And Anthony happened to stop in just the right place.
0:35:21 > 0:35:24If I'd been one step higher or one step lower,
0:35:24 > 0:35:25I wouldn't have noticed it.
0:35:30 > 0:35:31Imagine that.
0:35:31 > 0:35:35Lurking out there in the dark, all across the UK,
0:35:35 > 0:35:38there's green gold just waiting to be discovered.
0:35:38 > 0:35:40Fantastic.
0:35:42 > 0:35:46For our final dose of weirdness, we head to southern Spain.
0:35:51 > 0:35:55Normally, Calasparra is a small, sleepy town.
0:35:59 > 0:36:05But in November 2015, a local farmer found something out of this world.
0:36:08 > 0:36:12A peculiar, alien object appeared out of nowhere.
0:36:17 > 0:36:20- TRANSLATION:- I saw a black ball about 60 centimetres across
0:36:20 > 0:36:23lying close to the bottom of the bank,
0:36:23 > 0:36:25and a big dent where it hit the ground.
0:36:30 > 0:36:33When I saw it, I called the police straightaway.
0:36:33 > 0:36:35They told me not to touch it.
0:36:37 > 0:36:40The police cautiously collected the huge hairy ball
0:36:40 > 0:36:42and took it away for analysis.
0:36:44 > 0:36:46And this wasn't a one-off.
0:36:46 > 0:36:51That month, two more of these eerie orbs turned up in the region.
0:36:53 > 0:36:57And around the globe, there were reports of more weird objects
0:36:57 > 0:37:01suddenly appearing. These odd balls turned up in Vietnam.
0:37:04 > 0:37:06Another was discovered in Brazil.
0:37:07 > 0:37:10But where had they all come from?
0:37:12 > 0:37:14Back in Spain, there was a clue.
0:37:19 > 0:37:22- TRANSLATION:- Witnesses in the town said they saw strange objects,
0:37:22 > 0:37:26like a cluster of fire, which then dispersed and fell.
0:37:31 > 0:37:36They told me there were between four and six unidentified flying objects.
0:37:36 > 0:37:39Burning UFOs falling from space.
0:37:39 > 0:37:42Understandably, the mayor was very concerned.
0:37:43 > 0:37:47We were worried that it might happen again, falling on a primary school,
0:37:47 > 0:37:49someone's home, or a playground.
0:37:51 > 0:37:56So what could explain these menacing missiles that tumbled to Earth?
0:37:57 > 0:37:58Whoa!
0:37:59 > 0:38:04Well, our skies are the scene of some strange sights.
0:38:04 > 0:38:08One possibility is that they were some sort of mysterious meteorite.
0:38:10 > 0:38:13This one caused confusion when it landed in Kenya.
0:38:13 > 0:38:17'Residents of the Ol Donyo Sabuk area hear a loud noise
0:38:17 > 0:38:20'from the sky above. But there's no aircraft in sight.
0:38:20 > 0:38:23'Instead, a strange object, whose appearance left many puzzled.'
0:38:23 > 0:38:27And, you know, falling meteors are more common than you might think.
0:38:29 > 0:38:33Every day, the Earth is bombarded with thousands of pieces of rock
0:38:33 > 0:38:35that come from outer space.
0:38:35 > 0:38:37Now, as they enter the atmosphere,
0:38:37 > 0:38:41a tremendous friction is generated and they burst into flames.
0:38:41 > 0:38:46But if they survive that re-entry, then they become meteorites.
0:38:46 > 0:38:50Irregularly shaped, really heavy pieces of rock.
0:38:55 > 0:38:58But these space balls clearly weren't made of stone.
0:39:02 > 0:39:06So if they weren't meteorites, what were these alien orbs?
0:39:10 > 0:39:14At first, the scientist tasked with analysing the space balls was
0:39:14 > 0:39:16absolutely flummoxed.
0:39:16 > 0:39:20What a strange artefact. What a strange object.
0:39:20 > 0:39:23I've never seen anything
0:39:23 > 0:39:25similar before.
0:39:27 > 0:39:30Juan Antonio tested every bit of the ball.
0:39:33 > 0:39:35We found out
0:39:35 > 0:39:39the cover of the balls was made of carbon fibre.
0:39:39 > 0:39:41We discovered that
0:39:41 > 0:39:48some parts of the balls were made of a special stainless steel,
0:39:48 > 0:39:51and the metal of the main body
0:39:51 > 0:39:53was made of titanium.
0:39:54 > 0:39:56Right, so let's just get this straight.
0:39:56 > 0:40:00Fireballs, made of carbon fibre and titanium,
0:40:00 > 0:40:03are battering us from beyond our planet?
0:40:03 > 0:40:06So are these cannonballs a sign of intelligent life?
0:40:06 > 0:40:08Well, yes.
0:40:18 > 0:40:23You see, they are from outer space, but we put them there.
0:40:25 > 0:40:28These balls are fuel tanks, yes.
0:40:28 > 0:40:32Fuel tanks for powering rockets.
0:40:32 > 0:40:34'One small step for man.
0:40:34 > 0:40:37'One giant leap for mankind.'
0:40:37 > 0:40:41Since we began exploring space in the 1960s,
0:40:41 > 0:40:45nearly 7,000 satellites have been sent into orbit.
0:40:47 > 0:40:50And the metal balls found in Calasparra,
0:40:50 > 0:40:51Vietnam and Brazil
0:40:51 > 0:40:54are the remains of the small fuel tanks that are used
0:40:54 > 0:40:59to manoeuvre them. So, if they're supposed to be up in space,
0:40:59 > 0:41:02how did these fuel tanks end up in Spain?
0:41:04 > 0:41:07Well, sometimes satellites may break down or collide
0:41:07 > 0:41:10and the debris can fall back to Earth,
0:41:10 > 0:41:12or de-orbit.
0:41:12 > 0:41:15In a given month, 10 or 20 objects will de-orbit,
0:41:15 > 0:41:17that means they'll burn up in the atmosphere.
0:41:20 > 0:41:24When we have control over a de-orbit, we nearly always aim for the
0:41:24 > 0:41:27middle of the Pacific Ocean because it's a very big, uninhabited area.
0:41:27 > 0:41:30The problem is, when certain larger bits of debris de-orbit,
0:41:30 > 0:41:32larger pieces, fuel tanks etc,
0:41:32 > 0:41:34we have no control over where they'll land.
0:41:34 > 0:41:37We really won't know until very late in the de-orbit process.
0:41:41 > 0:41:43Whilst most debris burns up,
0:41:43 > 0:41:47robust parts like fuel tanks may survive re-entry.
0:41:47 > 0:41:52Realistically, space junk poses little risk of injury.
0:41:52 > 0:41:55It's much more dangerous hurtling around our planet.
0:41:55 > 0:41:58A paint fleck will have the same kinetic energy as a rifle bullet,
0:41:58 > 0:42:02and poses a real danger to spacecraft and asteroids.
0:42:04 > 0:42:07There are now millions of bits of debris circling the Earth.
0:42:07 > 0:42:10Some as big as a bus.
0:42:10 > 0:42:12And any collisions with the satellites we rely upon
0:42:12 > 0:42:15could jeopardise our whole way of life.
0:42:15 > 0:42:18The internet may go down because we rely on space-based communications
0:42:18 > 0:42:21more than ever in our connected society.
0:42:21 > 0:42:23A lot of the banking industry and finance industry relies on
0:42:23 > 0:42:26very accurate timing for high-frequency trading.
0:42:26 > 0:42:30If we lost those timing signals, there could be financial chaos.
0:42:31 > 0:42:35But don't worry, a global meltdown is highly unlikely.
0:42:35 > 0:42:39Space debris is very carefully monitored so that satellites
0:42:39 > 0:42:41can be moved out of harm's way.
0:42:42 > 0:42:47So, those strange Spanish balls weren't a sign of an alien attack.
0:42:47 > 0:42:52They were a symbol of the ever-increasing mass of space junk
0:42:52 > 0:42:54that's circling our planet.
0:42:55 > 0:42:59So, while Spain fell under attack by balls from space...
0:43:01 > 0:43:04..an equally strange sphere was found underwater...
0:43:06 > 0:43:09..and a mythical moss was uncovered underground.
0:43:12 > 0:43:17So there. Just goes to prove that although the weird and the wonderful
0:43:17 > 0:43:20can turn up in every corner of the globe,
0:43:20 > 0:43:24the extraordinary is just as likely to appear on your doorstep.