This cute and cool little fellow, the water bear, space bear, or moss piglet (Tardigrada) is far more resilient than it may look, being no longer than 1,5 mm.
“Tardigrades can survive for a few minutes at temperatures as low as −272 °C or as high as 150 °C, and −20 °C for decades. They withstand pressures from virtually 0 atm in space up to 1200 atm at the bottom of the Marianas Trench. They are also resistant to radiation levels ∼5000–6200 Gy.”
The Resilience of Life to Astrophysical Events (Nature)
Meet the tardigrade, the toughest animal on Earth - Thomas Boothby (TED-Ed)
It would be really interesting to see how the moss piglet has evolved. Why does it survive “virtually 0 atm in space”? When is that needed? To survive at the bottom of the Mariana Trench makes more sense.
It is indeed a successful construction. It has been around for 530 million years (since early Cambrian) and survived several extinctions, including the “Big five”.
Yes, it would be interesting to know. Why it evolved abilities which far exceed extremes of environment is still an unresolved puzzle.