Is there life on Mars? In 2024, NASA's rover Perseverance found a rock with small spots that look like a leopard's skin. The spots have two kinds of iron minerals and some materials with carbon.

On Earth, tiny living things often help make these. In 2025, NASA said this is the clearest sign so far of possible past life. But it is not proof, because chemistry alone can sometimes make these spots.

In July 2024, NASA's Perseverance rover examined a rock called Cheyava Falls in an old river valley in Jezero Crater on Mars. The rock is a mudstone, which forms from fine mud in places with water. On its surface were small spots with light centers and dark edges, like a leopard's skin.

Instruments on the rover found two iron minerals, vivianite and greigite, along with organic matter. On Earth, these minerals are often produced by chemical reactions that microbes use to get energy. In 2025, scientists reported the findings in Nature and called them a potential biosignature, a possible sign of past life. However, similar minerals can also form without life, so this is not proof.

In September 2025, researchers on NASA's Perseverance team reported in Nature what NASA described as the clearest potential sign of ancient life yet found on Mars. In July 2024, the rover studied Cheyava Falls, a mudstone in a dried river valley in Jezero Crater, and collected a sample called Sapphire Canyon. The rock is dotted with small "leopard spots" with light centers and dark rims. Using instruments on the rover, the team identified two iron minerals, likely vivianite, an iron phosphate, and greigite, an iron sulfide, associated with organic carbon. These minerals appear to have formed through low-temperature reactions in which organic matter transferred electrons to iron and sulfur, reactions that microbes on Earth commonly use to obtain energy.

Because the rock shows no evidence of the high temperatures or acidity that could produce such minerals without life, a biological explanation seems plausible. Even so, non-biological pathways have not been ruled out, the rover's instruments cannot match laboratory analysis, and the plan to return samples to Earth faces an uncertain future due to budget issues. So the finding is classified as a potential biosignature rather than evidence of life.