MARS rover Curiosity has captured a picture of what appears to be a rat on the surface of Mars.

The 'Mars rat' looks as though it has four legs and a tail, pictured surrounded by rocks on the red planet.

A Japanese blogger believes to have discovered the life on Mars, according to UFO Sightings Daily, which said it "seems to resemble a rodent but also may be a lizard".

"With water existing on Mars in small amounts, it's possible to find such desert animals wandering around … although very rare mind you," the post says.

Other possible explanations doing the rounds are that the object is a possum or a lizard.

Or, it could just be a rock that looks like a rat.

What do you think?