Behold the Mightly Tardegrade aka: I love Water Bears.

Abandoned in dry water holes, these barren animals can be exposed to heavy doses of X-rays, gamma rays, neutrons, proton beams, high energy electrons, and ultraviolet radiation with no ill effects. Embryonic cysts of an ephemeral pool crustacean were actually dangled outside of the space shuttle, exposed directly to the cold and radiation of outer space, and were later brought back to earth and added to water, where they came to life within minutes. The universe could be accidentally colonized by such creatures. In a sadistic array of experiments, adult tardigrades, also known as water bears, were once kept for eight days in a vacuum, transferred into helium gas at room temperature for three days, and then exposed for several hours to nearly -450 degrees Fahrenheit. Placed in water at room temperature, they returned to life, no questions asked.

Perhaps the most telling experiment is that anhydrobiotic cysts of crustaceans are packaged and sold to children. Often they are sold as "sea monkeys," presented on packages with the females wearing pink bows in their sensory organs, and families of smiling crustaceans reclining in underwater living rooms (the wife wearing an apron, the husband smoking a pipe). At a toy store I once bought an envelope of Triops eggs (Desert Dan brand); the print on the back informed me that they would live twenty to seventy days, "unless, of course, they are eaten alive by their cannibal siblings."

The packaging read:
TRIOPS
From The Age Of
DINOSAURS
Watch
Their
AMAZING
AQUA-BATICS
They're
ALIVE
Just Add Water
They Hatch In
24 Hours
EVERYTHING YOU NEED TO GROW INSTANT PETS

I put them in a cup and within twenty-four hours small objects could be seen scuttling across the bottom. No false advertising. I instantly had pets. And they were, indeed, from the age of the dinosaurs, as Desert Dan had professed. The aquabatics would come later as they were eating each other. What truly separates these dehydrated organisms from every other living thing is that they have no metabolism. Even scientists who contend that all life requires a metabolism admit that anhydrobiotes must exist at the minutest fraction of the speed of normally metabolizing specimens. If this were a human, the heart would beat three times every year. But there does not appear to be even a slow heartbeat in anyhydrobiotes. Using radiochemical assay, researchers have not been able to detect enzyme activity in any "live" organisms below 8 percent water content by body weight. There appear to be no working parts in these organisms: they are as dead as rocks. If a Mars lander were to be in given a scoop of dust from a dry water hole and allowed to run all of the spores and shrimp eggs and desiccated adults of various species through its battery of life-finding tests, it would conclude that no life was ever present.