The methane has been found on Mars by NASA. But it can be from space, or from organisms, what has died the long time ago.
Curiosity-rover http://marxjatalous.blogspot.com/p/the-methane-has-been-found-on-mars-by.html Kimmo Huosionmaa There have been found methane on Mars, but that would not necessarily mean, that there would be found living bacteria. The gas might come from the bacteria, what have been dead the long time ago, and the gas might be stored inside the Martian landscape. Another change would be that the Methane and carbon are from the space, and dropped to the Mars with the meteorites. The methane would be the more interesting thing than free carbon because of this chemical combination forms on Earth mainly by the organic material rotten in the anaerobic conditions. And the carbon is one of the basic elements of nature. That element is found on the asteroid belt, and there have been found asteroids, what are pure carbon. Those asteroids are very uncommon particles in the group of little planets. Actually the moons of Mars, Phobos and Deimos are only known that sized carbon asteroid...