I approached her very, very slowly,' he says, 'and then drifted. It was a cat-and-mouse game.' When the bear slipped into the water, he just waited. 'There was just a flat, world of water and ice and ...

It's called a "tardigrade" or "water bear". It's just one of many aquatic invertebrates on the planet, but it's unlike any other life form that scientists know of. Less than a millimeter in size ...