Ziggy played guitar, and scientists in the U.K. played with a big chunk of dry ice to try to figure out what’s behind the strange alien patterns known as the “spiders on Mars.”

Those patterns, visible in satellite images of the Red Planet’s south pole, aren’t real spiders, of course; but the branching, black shapes carved into the Martian surface look creepy enough that researchers dubbed them “araneiforms” (meaning “spider-like”) after discovering the shapes more than two decades ago.