The Internet says thigh bone; NASA scientists say plain old rock.

Is the latest photo from Mars, snapped by the Curiosity rover and beamed back to Earth, proof that human-like aliens once visited the Red Planet? Many online conspiracy theorists seem to think so. Or is it just further evidence that erosion works in strange ways? That's what NASA researchers would have you believe.

But if NASA had something to hide, it's doubtful they would have shared the photo with the public in the first place. Mission science team members say the thigh-bone-shaped rock was most likely sculpted by the eroding forces of wind or water.

"If life ever existed on Mars, scientists expect that it would be small simple life forms called microbes," NASA officials wrote in a press release. "Mars likely never had enough oxygen in its atmosphere and elsewhere to support more complex organisms. Thus, large fossils are not likely."

Seems like sound logic, but facts don't often stand in the way of outlandish conspiracy theories.