These tiny, 1mm long creatures are possibly the most highly adapated and resistant creatures on our planet. They are also very common. Some of the 900 species have survived space, pressures way, way beyond those found naturally on Earth, heat and fire, temperatures almost as low as absolute freezing, dessication and almost anything else that can be thrown at them. They have some unique and special strategies and adapatations. This article is well worth a read, simply to get a handle on some extreme natural history as well as some amazing survival strategies.