Tardigrades can survive the most extreme conditions:
- Heat of up to 151° C and cold of almost 0° K
- Low pressure of a complete vacuum and high pressure of up to 1200 ATM
- 10 years without water
- 5000 Gy of radiation (5-10 is lethal for humans) and supposedly many environmental toxins
They took them to a low earth orbit and exposed them to open space for 10 days. More than two thirds of the animals survived and reproduced normally. Fascinating.