Martian Creepy Crawlers The European Space Agency's Mars Express orbiter has spotted mysterious "spiders" roaming the Red Planet's southern polar region. But they're not the arachnids we've come to fear back on Earth — they're the result of a complex geological process that causes carbon dioxide to sublimate, bringing darker material from below the surface […]

The European Space Agency’s Mars Express orbiter has spotted “spiders” on the Red Planet’s southern polar region.

But they’re not the arachnids we fear or adore back on Earth — they’re the result of a complex geological process that causes carbon dioxide to sublimate, digging up darker material from below the surface during the planet’s spring.

And they’re a whole lot larger than the spiders you’re used to, measuring up to 3,300 feet across.

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Many of these spots have been found outside of a Martian landscape dubbed Inca City (formally Angustus Labyrinthus) thanks to its geometric ridges that summon to mind Inca ruins.