THE BIZARRE MARTIAN ZOO THAT ALIEN HUNTERS HAVE SPOTTED ON MARS

It has become a popular past time in some of the stranger corners of the internet - searching for rocks that look like animals in photographs sent back by Nasa's Mars rovers.

Among the recent creatures to join this red planet 'zoo' is one that looks like a silver back gorilla.

Beside it, eagle eyed enthusiasts say there is another rock that looks much like a camel.

Others have said the two rocks look more like a mother bear and its cub.

Videos posted by a mysterious animal and UFO enthusiast calling himself Mister Enigma also claimed to have spotted an octopus like creature on Mars and an Egyptian statue built by Martians.

Previously conspiracy theorists have found everything from 'crabs' and 'lizards' to 'bears' and 'rabbits', by combing images of the red planet taken by rovers such as Curiosity.

Of course, however, the majority of experts believe they are simply interestingly-shaped rocks and it is a clever trick of the mind that makes us think we're seeing creatures.

In October last year, UFO hunters spotted a baby bear on Mars and claimed that it was alive, based on its 'hair' and shadows seen around its body.

It was pinpointed by YouTube user Paranormal Crucible among photos of Gale Crater taken by Nasa's Curiosity rover, who alerted the website UFO Sightings Daily.

Site editor Scott C Waring, who is based in Taiwan, said: 'There is a reason Nasa puts photos into black and white. To hide the living creatures and plants that are an obvious colour.

One month earlier, a blogger claimed to have seen a lizard meandering around Mars.

The claim, posted again on UFO Sightings Daily, caused some excitable conspiracy theorists to fear Nasa could be planting life on the planet for scientific testing.

'With water existing on Mars in small amounts, it's possible to find such desert animals wandering around...although very rare mind you,' Mr Waring wrote on his site.

In November 2013, a 'fossilised Martian lizard' caused considerable excitement.

The mysterious object was first spotted by UFO Sightings Daily which uncovered the photograph in Nasa's archives.

It would be easy to miss, but the keen eye of Scott Waring, who owns the site, was able to spot the 'iguana' rock in photos taken by the Mars Curiosity rover.

In August, alien hunters shared an image on 'Journey to the Surface of the Mars' Facebook page of a mysterious Martian 'facehugger crab,' which they noted bears some resemblance from the monster in 'Alien'.

A year previously, alien hunters spotted a 'frog' on Mars (pictured above). The dubious discovery was made by Jason Hunter who shared a video showing the amphibian-shaped rock on YouTube

The 'crab' can be seen in an image taken by the Mars rover Curiosity, which shows a formation that looks like a cave mouth on the red planet.

A year previously, alien hunters spotted a 'frog' on Mars.

The dubious discovery was made by Jason Hunter who shared a video showing the amphibian-shaped rock on YouTube.

Other small animals have also been spotted, including a rat, eagle and rabbit.

Photographed in 2014, Nasa admitted that its Opportunity rover had snapped an object that resembled a rabbit.

Jeff Johnson, a scientist from the US Geological Survey was alerted to a small 'fuzzy-looking object' measuring about two inches long (4-5cm).