it's a bug...
it lives on algae.. when moss dries up, it also dries up and "goes
to sleep" and may lose up to almost all the water in its body and
when there's water again, it just absorbs it and then comes alive
again..
when in the total dehydration state, it survives almost anything,
organic solvents, mineral acids, radiation, liquid nitrogen... and
it is still alive! and all it needs is a drop of water for it to
pop back to life 
cool isn't it? 
