If you haven't heard of a tardigrade before, prepare to be wowed. These clumsy, eight-legged creatures, nicknamed water bears, are about half a millimeter long and can survive practically anything: freezing temperatures, near starvation, high pressure, radiation exposure, outer space and more. Researchers reporting in the journal Nano Letters took advantage of the tardigrade's nearly indestructible nature and gave the critters tiny "tattoos" to test a microfabrication technique to build microscopic, biocompatible devices.