The European Space Agency's Mars Express orbiter recently returned some interesting images of Mars, that appeared to show large groups of... spiders?

No, they aren't spiders. We can all relax, even the most afflicted Martian arachnophobes.

The ESA said in a news release that one of its Mars Express orbiter captured images of the "spiders," which are really just small, dark-colored features that begin to be formed when sunshine falls on carbon dioxide deposited during the planet's winter months. The light causes the carbon dioxide ice at the bottom of the deposits to turn into gas, which eventually bursts through ice that can be up to three feet thick, shooting dust out in geyser-like blasts before settling on the surface, the space agency said.

While the spots might look tiny from space, they're actually fairly large. The ESA said that the patches are as small as 145 feet wide, at their largest, might be over half a mile wide. Below those large spots, the arachnid-like pattern is carved beneath the carbon dioxide ice, the ESA said.

The spider patterns were observed by the ExoMars Trace Gas Orbiter, which launched in 2016 and has been studying Mars for signs of possible past life. The majority of the dark spots captured by the orbiter appear on the outskirts of a part of Mars nicknamed "Inca City" because of its "linear, almost geometric network of ridges" reminiscent of Incan ruins. The area, discovered in 1972 by a NASA probe, is also known as Angustus Labyrinthus, and is near the planet's south polar cap. 

David Bowie's estate has not returned a request for comment.

See Related: NASA Warned: Moon's Resources Could Be Destroyed by 'Thoughtless Exploitation.' So What? 

NASA Asked to Help Search for... Wait, the Loch Ness Monster? Seriously?

The human brain is, in large part, a big pattern-recognition engine. That's how we recognize the faces of our friends and loved ones. That's why we can look at a cloud and see a dragon, or look at one of these Mars Express orbiters and see spiders.

There are, however, efforts underway to determine if Mars, which was in the distant past warmer and moister, ever harbored life.

While we go about our daily lives on Earth, a nuclear-powered robot the size of a small car is trundling around Mars looking for fossils. Unlike its predecessor Curiosity, NASA's Perseverance rover is explicitly intended to "search for potential evidence of past life", according to the official mission objectives.

Jezero Crater was chosen as the landing site largely because it contains the remnants of ancient muds and other sediments deposited where a river discharged into a lake more than 3 billion years ago. We don't know if there was life in that lake, but if there was, Perseverance might find evidence of it.

If Perseverance does indeed find any signs of past life - speaking as a biologist - it will likely be the Martian equivalent of bacteria or some kind of colony of organisms like a stromatolite; Mars was not that warm and that wet for that long, after all. And anything the rover does find may not necessarily be recognizable as life. After all, life on Mars, if there ever was any, would be alien, possibly not even recognizable as life to us. There will not, sadly, be any beautiful Martian princesses wearing nothing but jewels; no thoats, no Tharks, no Kingdom of Helium, but possibly, and more likely, some kind of self-replicating microscopic thing that we might not even recognize as life.

And certainly, no spiders.

That doesn't make the effort any less interesting, though.

This seems appropriate.