'...not as we know it...'

Another strange discovery is a previously unknown Deinococcus — a group of bacteria known as the world's toughest — capable of tolerating γ-ray exposures 5,000 times greater than those survived by any other known organism, despite living 15 metres beneath the permafrost. These levels of radiation have never existed on Earth, so the source of the bacterium's resistance is a mystery. Theories put forth so far include that the microbe had an extraterrestrial origin...[and] at this point, no theory has been discarded.

-- from Antarctic microbes live life to the extreme