http://www.newsweek.com/these-mars-rocks-could-hold-vital-clues-life-red-planet-945786

Iron-rich rocks found near ancient lake sites on Mars could hold vital clues as to whether life once existed on the Red Planet, according to new research published in the Journal of Geophysical Research.

An international team of researchers, led by scientists from the University of Edinburgh, suggest that these rocks should be prime targets for upcoming missions—such as NASA’s Mars 2020 rover—which are designed to search for signs of life. This life, if it exists, will likely take the form of tiny microbes, scientists think.