The latest discovery from NASA’s Curiosity Mars rover is a field of honeycomb-shaped polygons covering a Martian valley called Valle Grande. As Gizmodo reports, Curiosity has snapped pictures of the unusual terrain texture before, called polygonal fractures, each about 1.5 to 3 inches wide, but NASA says it’s previously only found them in small patches, “nothing on the scale discovered in Valle Grande.”

Curiosity captured a 360-degree panorama of the “sea of polygons” on June 19th and 20th (Martian sols 4,930 and 4,931) that shows the texture spreading out in all directions. Project scientist Ashwin Vasavada says the Curiosity team “measured their shapes and chemistry carefully and are hopeful there are clues in the data as to how these features formed.”

NASA says billions of years ago, “lakes and streams dappled the lower foothills of Mount Sharp, a 3-mile-tall (5-kilometer-tall) mountain that Curiosity has been ascending since 2014.” This terrain could also indicate there was once water in Valle Grande, based on previous polygon patches:

Some of the polygons that the mission has spotted in the past clearly formed as mud cracks, though a variety of processes can contribute to their honeycomb textures, including cycles of warm and cold temperatures or compression that squeezed water out of the sediment when the surface was buried.