"Life finds a way."  Thanks to a research time involving Princeton, Indiana University, and others, that isn't just a sappy Disney quote - it's an incredible fact.  They found extremophile bacteria buried over two miles into solid rock, where the life-giving energy of the sun never reaches - the energy every other species on Earth depends on.  Instead they found their own power source - radiation!

The hardy organisms have a unique biology with a very refined palate, consuming the by-products of radioactive breakdown to stay alive. Uranium decay cracks water molecules apart, recombining into peroxide (which you might know as bleach).  This combines with fool's gold (pyrite) to release ions, which the cells' specialized metabolism can derive energy from.  To summarize: these things sit on uranium, drink bleach and eat solid rock, thereby making every single "Iron Stomach" contest in human history look like a day at the buffet.  Hell, these things make Batman look like a daycare attendant.