A photograph sent from Mars by one of Nasa's two rovers last week shows what conspiracy theorists have described as a "beam of light" shining up from the planet's surface.
Nasa has yet to issue an official explanation for the image, which has been doing the rounds of the internet since it was posted by UFO enthusiast Scott Waring on Sunday.
Waring wrote on his UFO Sighting Daily website that the image could prove "there is intelligent life below the surface that uses light as we do".
"This is not a glare from the sun, nor is it an artifact of the photo process," he said.
'Look closely at the bottom of the light. It has a very flat surface giving us 100% indiction it is from the surface. Sure NASA could go and investigate it, but hey, they are not on Mars to discovery life, but there to stall its discovery."
It's not the first time a photo sent back by the Mars rovers has piqued the interest of web users.
In January, a white object dubbed the "jelly doughnut" mysteriously appeared in a photo where it had not been 12 days earlier.
Some claimed the artefact was a Martian plant that had bloomed, while others more rationally said it could have been a meteorite.
Nasa, however, had a simpler explanation for the appearance of the stone, saying one of the rover's wheels had simply flipped it over.