Tardigrades

Meet tardigrades (commonly known as water bears or moss piglets), one of the most interesting species on the planet. They are not afraid of extreme high and low temperatures, pressure and radiation. Boiled water and liquid helium doesn't scare them. Tardigrades can survive almost a decade without water. And they are the only animals known to be able to survive the vacuum of space. And yes, they are very tiny. The biggest adults may reach a body length of 1.5 mm, the smallest below 0.1 mm.