NASA announced Wednesday that it may have found the “clearest sign of life” to date on Mars.

Intriguing “leopard spots” on a rock sample collected by the Perseverance rover are being hailed as a potential biosignature, though scientists caution that further study is needed to confirm a biological origin. The discovery does not indicate current life, only ancient life on the red planet, where the average temperature is -80 degrees Fahrenheit.

Still, the rock sample, named Sapphire Canyon, thrilled scientists and the acting NASA administrator, Sean Duffy.

“After a year of review, they have come back, and they said, ‘Listen, we can’t find another explanation.’ So this very well could be the clearest sign of life that we’ve ever found on Mars, which is incredibly exciting,” Mr. Duffy said.

The sample was drilled from a rock called Cheyava Falls on the edge of the Neretva Vallis river valley, an area sculpted by water more than 3 billion years ago. After more than a year of analysis, the findings were published in the journal Nature.

The Perseverance rover, which landed in Mars’s Jezero Crater in February 2021, has been hunting for rocks altered by ancient water. The Cheyava Falls sample, collected in July 2024, immediately stood out. Its unique black markings — nicknamed “poppy seeds” and “leopard spots” — along with detected organic compounds, suggested it might hold secrets to Mars’s past.

On Earth, such features could indicate that chemical reactions once supported microbial life. The rover’s instruments found that the spots are rich in iron and phosphate, while white veins of calcium sulfate prove that water once flowed through the rock.

“The discovery of a potential biosignature … is something that we’re sharing with you all today that grows from years of hard work, dedication and collaboration,” a Perseverance project scientist at NASA’s Jet Propulsion Laboratory, Katie Stack Morgan, said during a press conference Wednesday.

One theory about the formation of the rock is that chemical reactions with hematite — a mineral responsible for Mars’s red color — turned the rock to white from red, releasing iron and phosphate and creating the black rings. Such reactions can also provide an energy source for microbes.

Since its landing, Perseverance has been collecting samples intended for a future return mission to Earth. However, the path for bringing them home is unclear, as NASA faces potential budget cuts that could impact the Mars Sample Return program.

“We’re looking at how we get the sample back,” Mr. Duffy said. “What we’re going to do is look at our budgets, we look at our timing, and … what technology do we have to get samples back more quickly?”

For now, the rock remains in a tube millions of miles away, holding what could be the key to one of humanity’s most pressing questions.