Why it matters: This discovery "is the closest we've actually come to discovering ancient life on Mars," said Nicky Fox, associate administrator of NASA's science mission directorate, at a Wednesday briefing on the findings of the study that were published in the journal Nature.
* Sean Duffy, NASA's acting administrator, said at the briefing the discovery could "very well could be the clearest sign of life that we've ever found on Mars," though officials emphasized that more research was needed.
Driving the news: Perseverance was exploring the "Bright Angel" formation, a set of rocky outcrops in the ancient river valley of Neretva Vallis "that was carved by water rushing into Jezero Crater long ago," when it encountered the rocks, per a NASA statement Wednesday.
* "The rover's science instruments found that the formation's sedimentary rocks are composed of clay and silt, which, on Earth, are excellent preservers of past microbial life. They also are rich in organic carbon, sulfur, oxidized iron (rust), and phosphorous."
* These mudstones are dotted with markings that scientists have dubbed "leopard spots" and "poppy seeds," according to the study.
* Perseverance scientist and lead author of the study, Joel Hurowitz, of Stony Brook University in New York, noted at the briefing that microbes "will eat the organic matter and react it with the mud, and the byproduct of that reaction is these minerals."
Zoom in: "[O]ur analysis leads us to conclude that the Bright Angel formation contains textures, chemical and mineral characteristics, and organic signatures that warrant consideration as 'potential biosignatures,'" the scientists wrote in the study.
* Fox said at the briefing that this signature is like a "leftover sign," rather than life itself.
* "It's like seeing a leftover fossil. Maybe it was a leftover meal, maybe that meal's been excreted and that's what we're seeing here," Fox said.
* "It certainly could have been from ancient life, and that would have been something that was there billions of years ago, nothing that's currently there," Fox added.
* "We're kind of one step closer to answering one of humanity's most profound questions, and that is: are we truly alone in the universe?"
Of note: Janice Bishop, a planetary scientist at the SETI Institute in California, and Mario Parente, an expert in remote sensing on planets at the University of Massachusetts Amherst, wrote in an accompanying article to the report: "There is no evidence of microbes on Mars today."
* However, they noted that "if any had been present on ancient Mars, they too might have reduced sulfate minerals to form sulfides in such a lake at Jezero Crater."
Between the lines: "Intriguing data from the Perseverance rover on Mars, but too soon to attribute it to the existence of life," wrote science writer and theoretical physicist Sean Carroll, who was not involved in the study, on Bluesky Wednesday.
* "Science takes time, that's okay."
What we're watching: Returning the core sample collected from this unit for analysis "using high-sensitivity instrumentation on Earth will enable the measurements required to determine the origin of the minerals, organics and textures it contains," the scientists write in the paper.
* Some scientists and advocacy groups have raised concerns about Trump administration funding cuts to NASA programs.
* Duffy said officials were looking at how to get the samples that the Perseverance Mars rover has collected back to Earth.
* "What we're going to do is look at our budgets, we're going to look at our timing and how do we spend money better and what technology do we have to get samples back more quickly," Duffy said. "So that's a current analysis that's happening right now."