WASHINGTON -- Scientists have found new and compelling evidence of possible ancient microscopic life on Mars, NASA announced on Monday. An international team of researchers working with a Martian meteorite found in Antarctica discovered magnetite crystals embedded in the space rock that were arranged in long chains. Those chains could only have been formed by once-living organisms, the U.S. space agency said in a statement. "The chains we discovered are of biological origin," Imre Friedmann of NASA's Ames Research Center said in the statement. (Reuter)