Ангараг гаригаас эртний амьдралын ул мөр байж болзошгүй шинж тэмдэг илрүүлэв

The rock is shaped like an arrowhead, 3.2 feet by 2 feet, and NASA’s Perseverance rover came upon it in July 2024 at the edge of a dry river valley on Mars. Its reddish surface was covered in spots.

The rover team named the rock Cheyava Falls and called the marks leopard spots. Smaller specks, less than a millimeter across, became poppy seeds. Perseverance drilled a core from the rock, named it Sapphire Canyon and sealed it in a tube.

More than a year later, the team said what it thinks the spots are: the residue of a chemical reaction that microbes often run on Earth.

In a paper published in Nature on Sept. 10, 2025, researchers led by Joel Hurowitz of Stony Brook University reported that the spots and specks are enriched in two iron minerals, likely vivianite and greigite, and that the mudstone around them holds organic carbon. The carbon appears to have reacted with the mud to produce the minerals, at low temperatures, after the sediment was laid down.

It happened shortly after the mud settled on a lake bottom, Hurowitz told Reuters. On Earth, he said, microbes are often the cause. They consume the organic matter and produce the minerals as a byproduct of their metabolism.

Nobody on the team claims to have found life. The claim is narrower. Michael Tice, a Texas A&M University geobiologist and a co-author of the paper, said that on a closer look the team saw “things that are easy to explain with early Martian life but very difficult to explain with only geological processes.”

NASA files that under potential biosignature: something that might have a biological origin but needs more study before anyone can say.

Mud Full of Rust, Sulfur and Carbon

Cheyava Falls sits in the Bright Angel formation, light-colored outcrops on the northern and southern edges of Neretva Vallis, a quarter-mile-wide valley cut by water rushing into Jezero Crater. The rock is mudstone, made of clay and silt, and it is rich in organic carbon, sulfur, phosphorus and oxidized iron, which is rust.

That mix is potential fuel. Hurowitz said in NASA’s announcement that it could have been a rich source of energy for microbes.

It was not just the minerals that struck Tice but how they are arranged inside the spots, a pattern he said points to the chemical cycling of iron and sulfur.

“On Earth, things like these sometimes form in sediments where microbes are eating organic matter and ‘breathing’ rust and sulfate,” he said.

The carbon turned up in the same places. The rover’s SHERLOC instrument detected a spectral signature of organic carbon in several Bright Angel rocks. It was strongest at a target called Apollo Temple, where vivianite and greigite were also most abundant.

Organic does not mean alive. “It just means having a lot of carbon-carbon bonds,” Tice said. Organic carbon has been found on Mars before, and it can come from nonliving sources such as meteorites.

No Sign the Rock Was Ever Cooked

Vivianite and greigite can form with nothing alive nearby. NASA names three ways: sustained high temperatures, acidic conditions or binding by organic compounds. The Bright Angel rocks show no evidence of heat or acid, the agency said, and it is unknown whether the organic compounds in them could have driven the reaction at low temperatures.

Sulfur is the sticking point. Reactions between iron and organic matter could account for some features of the spots without life, according to Texas A&M’s summary of the paper. The known nonliving routes to the sulfur features usually work only at relatively high temperatures.

Everything the rover can measure suggests the rocks were never heated that way, Tice said. “If that’s the case, we have to seriously consider the possibility that they were made by creatures like bacteria living in the mud in a Martian lake more than three billion years ago.”

The case for life here is an argument by elimination, which is why the team stops short. Hurowitz told Reuters that the rover’s data alone cannot completely rule out nonliving chemistry. The question now, he said, is whether life made the features or whether nature “has conspired to present features that mimic the activity of life.” Katie Stack Morgan, Perseverance’s project scientist at NASA’s Jet Propulsion Laboratory, rated the nonliving explanations “less likely” but said they cannot be ruled out.

On Earth, Rocks This Old Have All Been Heated

Reuters put the rock’s formation at 3.2 billion to 3.8 billion years ago, when Jezero Crater is believed to have held water. Rocks of that age on Earth hold evidence of microbes working iron and sulfur the same way, Tice said, but not features like these.

“Processing by plate tectonics has heated all our rocks too much to preserve them this way,” he said.

Old as they are, the Bright Angel rocks are among the youngest sedimentary rocks Perseverance has examined. NASA called that surprising. An earlier hypothesis held that signs of ancient life would be confined to older formations.

The decisive tests need a laboratory. Instruments on Earth are far more sensitive than anything that can be sent to Mars, Tice said, and could read the isotopes in the organic matter, search for microfossils and determine the highest temperatures the rock ever experienced. That last measurement would show whether heat is still the best explanation for the spots.

Hurowitz told Reuters the ultimate tests can be done only “if and when” the core is brought back to Earth. When the paper was published, President Donald Trump’s budget proposal would have canceled NASA’s existing Mars Sample Return mission, Reuters reported, and acting NASA Administrator Sean Duffy said the agency would look at its budgets, its timing and what technology it had to get samples back more quickly.

Sapphire Canyon was still in its tube aboard the rover.

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