NASA has been searching for spiders on Mars since they were first spotted a few years ago. It was a daunting task. The team behind the Mars Reconnaissance Obiter had too many images to analyze without a little help. So they asked citizen scientists to offer a hand.

Martian spiders aren’t creatures, they’re features that are carved into the landscape by seasonal slabs of dry ice. When winter falls upon the Red Planet’s south pole, some of the carbon dioxide in the atmosphere condenses and forms polar ice caps. As spring returns, these caps thaw from the bottom up, the solid ice evaporates directly into a gas, and the process cuts “araneiform” (spider-like) channels into the landscape.

This geological process can’t be found on Earth so observing these features is of particular interest to scientists. Through the Planet Four: Terrains platform they asked volunteers to scan and classify images from the orbiter’s Context Camera (CTX) and High Resolution Imaging Science Experiment (HiRISE) to identify some of these unique formations. A year later, nearly 8,500 registered volunteers have helped scientists target specific regions for further imaging.

“It’s heartwarming to see so many citizens of planet Earth donate their time to help study Mars,” HiRISE Deputy Principal Investigator Candice Hansen said in a press release. “Thanks to the discovery power of so many people, we’re using HiRISE to take images of places we might not have studied without this assistance.”

The volunteers’s observations have helped identify 20 new regions for HiRISE’s seasonal monitoring of Mars.

But the hunt for spiders and other unique formations has just begun. With a fresh batch of CTX images recently added to the Planet Four: Terrain database, NASA welcomes any keen-eyed citizen scientists to join in the exploration and help unlock the geological secrets of the red planet.