It's not unusual for people to find things in space that look like other things. From the Man on the Moon to the Martian mountain that looks like a face, humans are apparently just wired to find recognisable shapes in the chaos.
The phenomenon, known as pareidolia, is a fairly common human trait.
So when an alien hunter declared that he'd found a lizard in a picture of the Martian surface taken by Nasa's Curiosity rover in 2012, we weren't all that thrilled.
And, sadly, neither is Nasa.
Above: The 'Space Lizard' in question (click here for the original).
Nasa has now confirmed that its rover will not be turning back - at a cost of several million dollars - to investigate the purported alien lizard/rat/rock.
"Clearly, it results from, you know, a lot of things like wind erosion and mechanical abrasion and breakdown chemical weathering of the rocks, as to why they get these weird shapes," said Curiosity deputy project scientist Joy Crisp, of Nasa's Jet Propulsion Laboratory, according to Space.com.
Instead of turning back to the mysterious lizard, the rover will instead head to Mount Sharp - a journey of about five miles that will take up to a year - to search for signs of ancient microbial life.
Before that it will complete tasks including an assessment of hydrogen abundance in the bedrock.
Still, at least Nasa isn't too bothered that people are more interested in space lizards (which don't exist) than space microbes (which might).
"It's fun in a way, too, in that it will attract a lot of the public to look at the images and learn a little bit about Mars by pulling them in this way" said Crisp.
Non-Habitable Rock vs. Habitable Rock
This set of images compares rocks seen by NASA's Opportunity rover (left) and Curiosity rover (right) at two different parts of Mars. The rocks observed by Opportunity were determined to have been uninhabitable due to high acidity, but the rocks observed by Curiosity were likely submerged in a more neutral liquid environment, raising the possibility that they could have once hosted life.
This image from Curiosity shows the first sample of Mars rock extracted by the rover's drill.
X-ray Diffraction Patterns
X-ray diffraction patterns of samples from two different areas on Mars' surface. On the left, a windswept, rocky environment that was likely uninhabitable; on the right, a lake-bed environment with likely neutral pH that may have been capable of supporting life.
A modern, Earth analog to the area NASA's Curiosity rover is currently exploring. Left, clay-bearing lake sediments exposed in a pit in southern Australia. Right, a core sample from the lakebed.
Left, a rock abraded by instruments on the Opportunity rover, showing reddish brown soil indicative of hematite, a substance not especially conducive to hosting life. Right, a hole drilled by Curiosity, showing the greyish, iron-rich rock underneath, which may be more compatible with habitability.
Curiosity Neighborhood Map
This map depicts the area in Gale Crater where the Curiosity touched down. The "John Klein Rock" is where Curiosity drilled its first soil sample.
A chemical analysis of a sample taken by Curiosity indicates the presence of water, carbon dioxide, oxygen, sulfur dioxide, and hydrogen sulfide released on heating.
The "John Klein" sample reveals the presence of simple carbon-containing compounds chloro- and dichloromethane in Mars' soil. These detections indicate that the analysis instruments are functioning properly and can continue searching for organic compounds.