NASA’s diligent rover has been investigating and sampling igneous fields and sedimentary rocks within the Ezero Crater, providing insights into the geological processes and intriguing characteristics of early Mars, while also searching for potential biological signatures. Upon entering Neretvavalis, on the western edge of Jezero Crater, the rover examined the distinct mudstone and con rock outcrops of the Bright Angel formation. A new paper published in the journal Nature details extensive geological, petrological, and geochemical studies of these rocks.

“Upon the rover’s arrival at the Bright Angel formation and while analyzing the local rocks’ composition, our team was notably surprised by their distinctiveness compared to previous findings,” stated Dr. Michael Tice, a geoscientist and astrobiologist at Texas A&M University.

“These findings offer evidence of chemical cycling that organisms on Earth can utilize to harness energy.”

“As we delved deeper, we observed phenomena that could easily be attributed to early Martian life, yet remain challenging to rationalize purely through geological processes.”

“Living organisms conduct chemistry that is naturally prevalent, provided there’s sufficient time and suitable conditions.”

“To optimize our understanding, the chemistry leading to these rocks necessitates either elevated temperatures or biological involvement, and we find no signs of high temperatures here.”

“Nonetheless, these results warrant experimentation and eventually lab studies of the samples collected to completely rule out non-biological explanations.”

The Bright Angel layer comprises mudstone (fine-grained sedimentary rocks composed of silt and clay) and water-laid sedimentary rocks featuring layered beds indicative of a lively environment with flowing rivers and stagnant water.

Employing various instruments from Perseverance, such as Sherloc and PIXL spectrometers, scientists identified organic molecules and small mineral arrangements likely formed through chemical processes related to redox reactions and electron transfers. On Earth, these processes are frequently driven by biological activities.

The most notable characteristics include small nodules and “reaction fronts” – referred to as “poppy seeds” and “leopard spots” by the rover team – consisting of iron phosphate (likely vivianite) and iron sulfide (probably greygeite).

These minerals typically arise in cold, water-laden settings and are frequently associated with microbial metabolism.

“The structural arrangement suggests that they formed through the redox cycling of iron and sulfur along with associated minerals,” Dr. Tice commented.

“On Earth, such formations often occur in sediments where microorganisms consume organic material and ‘breathe’ rust and sulfate. “

“Their existence on Mars provokes an intriguing question: Could a similar process have occurred there?”

The artist’s concept depicts the perseverance of NASA’s Mars Rover on the surface of the red planet. Image credit: NASA/JPL-Caltech.

The Sherloc instrument identified a Raman spectral feature known as the G-band, indicating the presence of organic carbon, in certain Bright Angel rocks.

The most substantial signal originated from a location called Apollo Temple, which exhibited high concentrations of both Vivianite and Greygeite.

“The concurrent presence of this organic matter and redox-sensitive minerals is quite compelling,” Dr. Tice noted.

“This implies that organic molecules might have facilitated the chemical reactions responsible for forming these minerals.”

“It’s crucial to recognize that ‘organic’ doesn’t invariably imply life creation.”

“This suggests the presence of numerous carbon-carbon bonds.”

“Alternative processes can yield organic compounds without biological involvement. The organic compounds identified here could have been synthesized either by or as a result of biological activity.”

“If they originated from an organism, decomposition through chemical reactions, radiation, or heat would have been required to yield the G-band we observe today.”

This research outlines two potential scenarios: Firstly, these reactions might be abiotic (driven by geochemical mechanisms) while microorganisms, similar to those on Earth, could have influenced these reactions.

Interestingly, although some features of the nodules and reaction fronts can be produced by non-biological reactions between organic matter and iron, established geochemical processes that can generate sulfur-related features tend to require relatively high temperatures.

“Every observation we’ve made regarding these rocks indicates that they haven’t been subjected to heat capable of producing leopard spots and poppy seeds,” Dr. Tice remarked.

“If that’s accurate, we must genuinely contemplate the possibility that such formations were created by bacteria-like life forms existing in the Martian lake sediments over 300 million years ago.”

Views of Perseverance path through Neretva Vallis and the formation of Bright Angels. Image credit: Hurowitz et al., doi: 10.1038/s41586-025-09413-0.

The research team underscores that while the evidence is not definitive proof of past life, the findings align with NASA’s criteria for potential biosignatures. This characteristic paves the way for further inquiries to ascertain the biological or non-biological origins.

Perseverance has collected core samples from a Bright Angel layer named Sapphire Canyon, which are currently housed in sealed tubes onboard the rover.

This sample is prioritized for future return to Earth in a prospective mission.

“Once we return this sample to Earth, we can investigate it using far more sensitive instruments than those we can deploy on Mars,” Dr. Tice explained.

“We could analyze the isotopic composition of organic materials, fine mineralogy, and conduct searches for microfossils if they exist.”

“More tests can also help determine the maximum temperatures these rocks were subjected to, and whether high-temperature geochemical processes are the most plausible explanations for any potential biological signatures.”

“The similarities between processes on Mars and Earth are indeed remarkable. However, there’s one crucial distinction.”

“It’s fascinating to note that life employs some of the same processes on both planets around the same epochs.”

“We observe signs of microorganisms in Earth’s rocks of similar ages where iron and sulfur interact with organic matter in comparable ways, but we don’t encounter the exact features seen in Mars’ ancient stones.”

Due to tectonic activities, the majority of Earth’s rocks have been altered significantly, making it unique and spectacular to witness this phenomenon on another planet.”

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Ja Hurowitz et al. 2025. Redox-driven minerals and organic associations at Jezero Crater, Mars. Nature 645, 332-340; doi:10.1038/s41586-025-09413-0

This article is based on a press release provided by Texas A&M University.