There are no pyramids, mermaids or 'crab monsters' on Mars, a Nasa scientist has said following numerous 'reports' of mystery objects spotted on the surface of the Red Planet. In recent years, UFO enthusiasts have been trawling through images sent back to Earth by Nasa's two Mars Exploration Rovers, finding objects that resemble those found on Earth. And these 'findings' have often made headlines around the globe.

Ashwin Vasavada, a project scientist with the Mars Science Laboratory, said that looking for signs of past life is more complicated than zooming in on a fuzzy picture. He told CNN, "We have colour HD cameras on this rover that far exceeds anything ever sent to the planet before, and yet in order to find these things that kind of trick your brain into thinking it's a mermaid or whatever, you do have to zoom in where it's kind of a fuzzy shadow at that point."

pyramid Mars Nasa rover
Nasa image of 'pyramid' on Mars Nasa

Instead, Vasavada points to a phenomenon called pareidolia, where your brain perceives a familiar pattern where none actually exists – like seeing a set of 'traffic lights' on Mars or Jesus's face on a piece of toast.

Talking about the 'tiny woman' spotted in a photograph in early August 2015, he said the 'figure' was in a spot they are studying. The area has a lot of sandstone next to mud that formed at the bottom of an ancient lake.

Drifts of sand now move down the hill, and while the shape looks a bit like a woman or mermaid, "she would be a few inches tall and hasn't moved in months, so we don't think that's what it is".

Indeed, he said that Nasa scientists would be thrilled to find the sort of 'evidence' thrown up online – but they are waiting for the real thing. "There is no group that would be [happier] to see such a thing than the 500 scientists around the world who work on this Curiosity rover. So far we haven't seen anything that is so obvious that it would be similar to what these claims are.

Curiosity rover
'Traffic light' on Mars NASA/JPL-Caltech/MSSS

"The thing that keeps coming back to me every single day is how un-weird it is, how much it looks like Earth. It's just fascinating that [on] Mars, even today, you can see the landscapes formed in similar ways that deserts and other places on Earth formed. It's kind of mind-blowing. We are working our way to answering what is a very difficult scientific question. It's unfortunately not going to be as easy as seeing a mermaid in a picture."