These animals can survive until the end of the Earth, astrophysicists say. Tardigrades, small animals which are about 1 mm in length and live in water and in moss and lichens, have a reputation as the toughest animals on the planet. Some of these microscopic invertebrates shrug off temperatures of minus 272 Celsius, one degree warmer than absolute zero. Other species can endure powerful radiation and the vacuum of space. In 2007, the European Space Agency sent 3,000 animals into low Earth orbit, where the tardigrades survived for 12 days on the outside of the capsule. The tardigrade lineage is ancient. Tardigrade microfossils are reported from the Early Cambrian to the Early Cretaceous, 520 million to 100 million years ago. They have seen the dinosaurs come and go.