Evidence that Mars once harbored alien life continues to mount. Just weeks after NASA's Curiosity rover detected spikes of methane in the Martian atmosphere--possible evidence of biological activity--a prominent geobiologist says she sees possible signs of past life in photos of the Martian landscape taken by the rover. "We can detect sedimentary structures in rocks on Mars using the rover images," Dr. Nora Noffke, an associate professor at Old Dominion University in Norfolk, Va., told The Huffington Post in an email. "The structures I describe belong to a group of microbial structures that form by the interaction of benthic (living on the ground) microbes with sediment dynamics (erosion) in clastic deposits such as sand." In other words, if such structures do exist on Mars, that suggests the planet may have once harbored microbial life. The microbes would have existed on Mars less than 3.7 billion years ago, Noffke said. Read more http://www.huffingtonpost.com/2015/01/08/life-on-mars-photos-scientist_n_6425392.html