White disc shapes revealed in images from NASA's Curiosity rover earlier this month have excited UFO enthusiasts.
The white rounded shapes were transmitted to Earth by NASA in images taken during its trip to Mars on August 5, the Huffington Post has reported.
Alien Disclosure Group UK's Stephen Hannard posted a video of four of the shapes online and highlighted them using a filter.
Mr Hannard describes the spots as "possible UFO sightings".
"What are these four objects? UFOs, Dust particles, or something else? As always you decide," he said.
However, the site reports the shapes have been dismissed as image "anomalies" or dead pixels by video analyst Marc Dantonio.
"All CCD [cameras] have them, and in a bland atmosphere like that at Mars, they would be very obvious as opposed to an active atmosphere like Earth, where they could end up hidden for a long time before anyone noticed them," Mr Dantonio said.
NASA is not believed to have commented on the footage.