Let's hope the Mars Rover has got a rat trap or two, because the Red Planet is infested with ... Martian Rats:
NASA’s Mars rover Curiosity snapped this panorama(above) of the “Rocknest” site with its MastCam camera on sol 52 (Sept. 28, 2012) of the mission. Now, with a keen eye and fertile imagination, a UFO enthusiast realized there was a camouflaged rodent hiding in the rocks. Needless to say, there’s no other evidence supporting this claim, it’s just something that looks like a rodent.
But as you may have guessed, after exercising an ounce of logical thought, what was once a cute furry four-legged creature suddenly becomes… wait for it… this is a good one… arock. And there you have it ladies and gentlemen: We’ve found a rock on Mars… that looks like a rat.
Ian O'Neill of LiveScience explains this Martian oddity: Link