Scientists in Europe are trying to find out more about a creature that few people have heard of and even less have set eyes on: the Pyrenean desman.
Not very much is known about these strange little beasts because they are really difficult to find - they only come out at night and live in streams in the mountain areas of Spain.
Although they look a bit like rats, desmans have long black snouts, which they use to sniff out food under water, and large webbed feet for swimming. They are about the size of a hamster, with a glossy grey coat.
Scientists are tracking the animals with micro chips because they are worried that their numbers are getting smaller. They examine them by trapping them in long, tube-saped mesh traps - but it's not easy!