The water bear can survive being frozen, boiled and even float around in space and live for 200 years

It's often said cockroaches could withstand a nuclear explosion. But another creature, dubbed 'nature's greatest survivor,' is even more invincible, and you've probably never even heard of it. Tardigrades, also known as water bears, are some of the most fascinating animals in world because they can live happily in the most extreme conditions.While not the most attractive creatures, the small, segmented animals come in many forms - there are more than 900 species of them - and they're found everywhere in the world, from the highest mountains to the deepest oceans. more