At first I was skeptical. Without breathable air, any flowing water at all, a food source, and trying to exist in a hostile climate, it seemed extremely doubtful - impossible in fact - that even a muscular, powerful rat could survive on Mars. However, after I'd viewed this photo with my own eyes, I was immediately convinced. There is no doubt in my mind, none whatsoever, that rats are - as we speak - wandering about on the surface of Mars. There could be billions of them. The only other explanation is that the rock just looks likes like a rat, and that's a completely absurd idea. As Sherlock Holmes would say, "When you have eliminated the impossible, whatever remains, however improbable, must be the truth."