They can survive temperatures near absolute zero or as high as 300 degrees. The crushing pressure at the bottom of the ocean doesn’t faze them, nor does the vacuum of space. Radiation 1000x the level strong enough to kill an elephant doesn’t slow the tardigrade down. They are so durable that scientists are either not able to make conclusions about them or they’re coming up with the wrong ideas.
The tardigrade, known also as a water bear (because they look and move like an 8-legged bear) or a moss piglet (because they love moss and look sort of like piglets), is a polyextremophile. Its ability to survive in the most inhospitable conditions gives it this moniker and it’s one of the most complex variations. NASA and other space agencies love playing with them. They even launched some into space and let them hang out on the outside of the International Space Station for some time before bringing them back in. Despite being exposed to the cold, barren vacuum of space while being bombarded by cosmic radiation, they made it home unscathed and even reproduced with no negative side effects from the exposure.
Not even Chuck Norris could have pulled that off.
One of the misconceptions that are currently being explored by scientists is using them to help validate the panspermia hypothesis. It basically says that life was seeded on earth from polyextremiphiles on other planets that reached ours after a collision on that planet propelled space rocks across the abyss to land on our planet and start populating it. As all creationists and most reputable scientists point out, this hypothesis has challenges with dealing with the origin of the life that is being hypothesized as the origins of life on earth. In science, it just doesn’t make sense to use the “turtles all the way down” argument.
Here’s an intriguing video about these little creatures as well as a few images of the buggers in action.