Spotted in a high resolution photograph taken by Curiosity on sol 52 of its surface mission at "Rocknest," the rock in question is an excellent example of pariedolia - a psychological phenomenon that tricks our brains into seeing familiar objects in random shapes - because when you see that rock, it sure looks like a rat. If this were a scene from a terrestrial desert where rats are known to live, then perhaps it could be a rat.
On Mars, however, where there is very little water, high radiation, low temperatures, thin atmosphere, and very little evidence of present-day organic chemistry, the only thing known to populate the plains are... rocks. So, using logic alone, this ‘rat' is a rock.
ANALYSIS: Is Mars Infested With Pareidolia Rats?
As silly as this little story may seem, mission scientists have put a positive spin on it: "It's fun in a way, too, in that it will attract a lot of the public to look at the images and learn a little bit about Mars by pulling them in this way," Crisp added.