Strange-looking signs and patterns were spotted on rocks on the Mars surface. At first glance, they may look mysterious or artificial, but science gives clear explanations. According to NASA, these markings are formed naturally by cracks, erosion, mineral veins, wind abrasion, and ancient water activity. Mars once had flowing water, and water can leave behind lines, grooves, and layered patterns in rocks. Extreme temperature changes on Mars also cause rocks to expand and crack over time, creatin