THIS mysterious monument could be proof there was once life on Mars.

The rectangular structure — measuring five metres across — was photographed by a super high resolution camera on the Mars Reconnaissance Orbiter.

The giant monolith juts out of the planet's surface casting a huge shadow below.

Its emergence on website Lunar Explorer Italia has got space buffs speculating if it could have been constructed by creatures once living on the red planet.

Evolution

The monument resembles the black monolith seen in Stanley Kubrick film 2001: A Space Odyssey.

In the movie the structure is believed to be a key to man's evolution.

And astonishingly Buzz Aldrin, the second man to walk on the Moon, revealed a similar monolith was detected on Mars' moon Phobos.

Speaking last week, he insisted: "We should visit the moons of Mars.

"There's a monolith there - a very unusual structure on this little potato shaped object that goes around Mars once every seven hours.

"When people find out about that they are going to say, 'Who put that there? Who put that there?'"

But scientists at the University of Arizona have cast doubt on the discovery saying the huge object is a "boulder".

A spokesman for the university's Lunar and Planetary Laboratory said: "It would be unwise to refer to it as a 'monolith' or 'structure' because that implies something artificial, like it was put there by someone for example.

"In reality it's more likely that this boulder has been created by breaking away from the bedrock to create a rectangular-shaped feature."