A huge mineral deposit in an unnamed Martian crater may be evidence of extraterrestrial life, according to new research by a leading earth scientist. Professor Mike Russell, of the Universities Research and Reactor Centre in Glasgow, believes a white, 18 kilometre long, lens-shaped body, sited near the rim of the crater, could be magnesium carbonate produced by microbial action in an evaporating lake. The scientist has studied similar deposits at Lake Salda in Turkey and believes the process, which on Earth involved cyanobacteria and diatoms, could also have occurred in Mars's wetter, warmer past. Russell's results, published in the Journal of Geological Society, pinpoint the site as a particularly good place for a future Mars mission to hunt for signs of life.