There are a number of things spotted on the surface of Mars that puzzle scientists, but one of them now has an explanation, according to a story on perfscience.com.

Researchers at NASA’s Jet Propulsion Laboratory believe they have figured out how mysterious spider-like formations are occurring on the Red Planet, and note they appear to be growing over time.

The Mars Reconnaissance Orbiter has been taking photographs of Mars’ surface since arriving at the planet back in 2006, and one of the first mysteries were the appearance of these formations.  They seem to radiate out from a central source, similar in appearance to the legs and the body of a spider.

Scientists now believe the channels are caused by thawing carbon dioxide (CO2), and that is the reason, along with shifting sand, they seem to be changing in appearance over a period of time.  The formations on the surface range in size from tens of yards, up to as much as hundreds of yards across, emanating from a central pit.

The researchers estimate it could take as much as 1000 Mars years for the features to develop, roughly 500 years in Earth time.

“We have seen for the first time these smaller features that survive and extend from year to year, and this is how the larger spiders get started,” stated Ganna Portyankina of the University of Colorado, Boulder

“These are in sand-dune areas, so we don’t know whether they will keep getting bigger or will disappear under moving sand,” continued Portyankina.

The sand dunes where the features are forming could play a factor in their growth or changing over time, as dunes tend to shift with blowing sand.  Portyankina added the researchers plan to monitor the channels to determine if they will continue to grow or at some point they will they be covered under the moving sand.

The study investigating the spider-like formations was recently published in the journal Icarus.