Tardigrades or water bears are tiny animals that are almost impossible to kill. Small as they may be, they are able to endure some of the harshest conditions discovered so far—like outer space!

Tardigrades can survive high doses of radiation, boiling temperatures, freezing temperatures, and crushing pressures. How? They possess the peculiar talent for entering a condition referred to as cryptobiosis, where they desiccate to almost all of their water content and form a small, dried-up ball. Under this state, they are able to remain in existence for decades without eating or drinking.

When their environment improves, tardigrades rehydrate and resume living—good as new. Researchers are examining them to gain knowledge about longevity, resiliency, and possible spaceflight life-support systems.

These micro-superheroes have been discovered on mountain tops, ocean deeps, and even in the Arctic. They survived mass extinctions and might keep surviving long after other species are gone.

In a way, tardigrades teach us that even the smallest creatures can possess the greatest survival secrets.