Conspiracy theorists believe a photo released by Nasa may show proof of life on Mars.
The picture from its Curiosity Rover mission contains a shadow on the surface of the red planet which resembles that of a "human-like" figure repairing the probe, it has been suggested.
An unnamed "source" said to have alerted the website UFO Sightings Daily about the picture pointed out that the "person" appears not to be wearing a helmet, with their short hair visible "in high detail".
"The person has on air tanks on their back and a suit that covers most of the body except the hair," the website claims.
Commenters on the site were mixed in their responses, with some saying the hair-like shadow is actually caused by "some fortunate placement of some rocks".
Another, however, said the picture was a "smoking gun" that appeared to prove human life on Mars.
The website's author suggests that the potential sighting may prove claims by Gary McKinnon, a British computer hacker who says US government files revealed the existence of "non-terrestrial officers" using the planet as their base.