From the tall mountains to the endless deep sea, from the hot springs to the Antarctic ice sheets, there were traces of water bears everywhere. They had evolved into a state of near-invincibility to cope with all kinds of harsh environment, where they would almost halt their metabolism as if they were dead. Yet, it was this kind of lingering on the verge of death which made them super hard to kill. The moment they were presented with life-threatening danger, they would enter a self-dehydration protection phase, which was also called cryptobiosis.
No need for food, no need for hydration, they could easily survive in an environment close to absolute zero or as high as 151 degrees. They could also endure the enormous pressure of the deep ocean, and tolerate radiation that was strong enough to instantly roast other animals. Even if you throw them into a poison bath, it wouldn't be a problem for them to survive.
