Mars images have always been something of a Rorschach test going back to the first images of the so-called "Face on Mars."

The latest is a snapshot taken by the Mars Curiosity which shows the shadow of the little rover... with maybe a little something -- or someone -- extra.

The image, captured in 2012 and available on the NASA website, shows what some people think is the shadow of a human, reaching up to make an adjustment, clean it up or maybe just mess with it (because we all know how Martians just LOVE to mess with us).


So what does it mean?

Maybe not a whole lot. But to Mars conspiracy theorists, it could be proof of several possibilities.

"This leaves us with three confusing thoughts," writes the UFO Daily Sightings blog.

"1st Is this proof that the rover is on Earth and not Mars and humans are cleaning it off and performing maintenance?

2nd Is this proof that humans are living on Mars in abandoned alien bases? (i.e. Gary Mckinnon hacker said he found such evidence on US govt computers).

3rd Is this proof that alien are messing with the rovers?"

The Snopes website has already dismissed the image as false.

"If UFO Sightings Daily were right about any of its three theories, would NASA have allowed this photograph to be published?" the website report reads. "Furthermore, why would it have kept the photograph up on its web site for three years?"

An expert cited by Snopes agrees.

"I think it is a case of seeing what we want to see, to confirm our expectations and hopes," Nigel Watson, author of the UFO Investigations Manual, told Snopes.

"This underlines the fact that such things literally lurk in the shadows and play with our imagination."

Others have dismissed the image as pareidolia, or the brain's tendency to turn unfamiliar images into something recognizable

"Pareidolia is hardwired into our brains. It is the reason why infants can recognizes faces almost as soon as they open their eyes," writes Viral Global News.

"It is the reason why clouds often appear as definite shapes and why some people have become wealthy on Ebay, selling items in which 'Jesus' has appeared," the website says. "The Virgin Mary embedded in a tree is an example of pareidolia. It is also this scientific phenomenon at work when people perceive that they have seen ghosts."

You can read more about the shadow over at The Huffington Post, and see more images from this unusual photo shoot on the NASA website.