Score another one for the extremophiles.
Biologists had already discovered organisms that can survive everything from high levels of radiation to vacuum to total darkness. Now they've found one that uses arsenic as a substitute for phosphorus, one of the six elements (carbon, hydrogen, nitrogen, oxygen, sulfur and phosphorus) we thought until now was necessary for life. Astrobiologists are excited, because it's one more way extraterrestrial life could evolve.
Like that search wasn't complicated enough already.
Read more here.
December 8 update: Not everyone's buying it.