The photo is just a weathered rock, the US space agency said.
"No bones about it! Seen by Mars rover Curiosity using its MastCam, this Mars rock may look like a femur thigh bone. Mission science team members think its shape is likely sculpted by erosion, either wind or water," the NASA statement read.
The photo shows the dirt-covered surface of Mars littered with bits of rock, one of which is elongated in a shape similar to a leg bone.
The image was first picked up on a UFO blog to show evidence of alien life on the Red Planet.
According to NASA, Mars never had enough oxygen for life to grow any bigger than microbes.