After police in Bristol were alerted to a possible sighting of a crocodile on the loose, Newsround takes a look at some of the best animal mysteries in the world.
Some were easily solved, while others still remain a mystery...
The Loch Ness Monster
'Nessie' has long been the biggest animal mystery in Britain. A grainy photograph from the 1930's allegedly shows an ancient long-necked water reptile coming out of the water.
Extensive surveys using sonar have failed to find any trace of the Monster but sightings continue to take place, research continues to be done and the mystery remains as to whether or not Nessie exists.
The Beast of Bodmin Moor
The Beast was reportedly a wild cat that was blamed for attacking livestock across farms in Cornwall. Although it was never proven, this skull was found near where the sighting had taken place.
There were more sightings of panther-like cats in the same region and came to be known as the Beast of Bodmin Moor.
Tiger on the loose...not quite
So this might look like a fearsome white Bengal tiger but it's actually just a stuffed toy. However that didn't stop eyewitnesses calling the police and sparking an area wide evacuation.
Police officers were deployed and a helicopter was scrambled to a field in Hampshire and the scare even stopped play at the Rose Bowl cricket ground. Police however realised it was a toy when it blew over in the helicopter down draft.
Bigfoot / Yeti
Also known as the 'Sasquatch' these beasts are usually described as a large hairy ape-like creature, in the range of 2-3 metres (6.6-9.8 ft) tall, weighing in excess of 230 kg. It's also covered in dark brown or dark reddish hair.
If it does exist, the bigfoot is thought to live in the forests of North West America but and the Yeti, also known as the Abominable Snowman, is thought to live in the Himalayan mountains of Nepal. Most scientists believe that these sightings are just combination of folklore, misidentification, or practical jokes.