By suspending their metabolism, the tiny invertebrates known as tardigrades or “water bears” can endure temperatures above 151° C (303° F) and as low as -272 °C (1 degree above absolute zero) for several minutes, and around -200° C (-328° F) for days on end. They can survive up to a decade without water, extreme exposure to gamma-ray radiation, pressures six times greater than those at the bottom of the Mariana trench, and at least ten days in the vacuum of outer space. This makes these relatively complex earthlings hardy enough to endure a stint on Neptune.