Amercian scientists believe that they may have found evidence that life once existed on Mars.

After studying rare minerals here on Earth, Dr Steven Ruff and Dr Jack Farmer, from Arizona State University, have suggested that unusual deposits on the Martian surface could have been created by microbes - a theory which, if true, could be one of the most significant in scientific history.

As Smithsonian reports, the process began when Nasa's Spirit rover discovered unusual deposits of opaline silica inside the Red Planet's Gusev crater in 2009.

Examining these minerals more closely, scientists found that they were covered in tiny cauliflower-shaped protrusions, for which they were unable to find an explanation.

The Gusev crater is in an area of Mars which astrogeologists believe was once covered in hot springs and geysers. However, like the rest of Mars, the area is now dry and barren, seemingly devoid of any signs of life and activity.

Explainer: Water on Mars

To investigate further, Ruff travelled to the Atacama Desert in Chile, an area so dry, lifeless and high above sea level that many scientists believe it's one of the most Mars-like environments on Earth.

Focusing his investigations on the El Tatio region of the desert, which is full of geysers, Ruff was surprised to find silica formations which looked similar to those which had been discovered on Mars, complete with the cauliflower-like protrusions.

Nasa finds flowing water on Mars - in pictures Show all 7 1 /7 Nasa finds flowing water on Mars - in pictures Nasa finds flowing water on Mars - in pictures The MAVEN spacecraft orbiting Mars EPA Nasa finds flowing water on Mars - in pictures Nasa finds flowing water on Mars - in pictures Nasa finds flowing water on Mars - in pictures Nasa finds flowing water on Mars - in pictures Nasa finds flowing water on Mars - in pictures Nasa finds flowing water on Mars - in pictures In this handout illustration provided by NASA/JPL, an artist's conception of the Phoenix Mars Lander on the Red Planet. Phoenix is slated to land on Mars on May 25, 2008.

Examples of this strange mineral formation have also been found in the US's Yellowstone National Park and the volcanic ground of the Taupo District in New Zealand. In both of these places, tiny fossils have been found which hold all the hallmarks of ancient microbial life.

If microbes created these formations in Yellowstone and New Zealand, they could have done the same in Chile. And it's not unreasonable to suggest that the identical formations on Mars could have been formed in the same way.

The link is far from conclusive, and although the Martian environment can be compared to areas on Earth in some ways, the two are still very different. Even if something looks very similar to a biological formation, that doesn't mean it actually is.

The formations, although fascinating and significant, are unfortunately not conclusive pieces of evidence that life has existed on Mars.

However, as Ruff and Farmer suggested to a meeting of the American Geophysical Union in December, if we are going to search for evidence of Martian life, these formations could possibly be a good place to look.