‘Alien arachnids’: Spider-like mounds captured by NASA on Martian surface (PHOTO)

Incredible spider-like mounds have been captured ‘crawling’ across the surface of Mars as winter drew to a close on the Red Planet.

An image, taken by NASA's Mars Reconnaissance Orbiter in May as the South Pole of Mars edged towards spring, shows patterns etched across the surface, freakishly similar in appearance to Earth’s eight-legged creatures.

“But these aren't actual spiders,”NASA clarifies in a post explaining the scientific process behind the distinct features.

The spider-like radiating mounds are known as “araneiform terrain,” and form when carbon dioxide ice below the surface heats up and releases. This is an active seasonal process not seen on Earth, according to the space agency.

The carbon dioxide ice on Mars changes from solid to gas as it warms, causing the gas to become trapped below the surface. Over time this trapped gas builds in pressure and breaks through the ice as a jet that emits dust.

READ MORE: ‘Once in a blue dune’: NASA shares striking image of Martian crater

The result is veiny spider-like ‘formations’ spread across the planet accompanied by dark spots formed by dust deposited around vents during the CO2 eruption.

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