A Nasa rover on Mars has discovered the first 'possible' signs of ancient life on the Red Planet.
Perseverance spotted what the space agency has described as an 'arrowhead-shaped' rock with 'veins' flowing through it.
Experts say the rock shows chemical patterns and structures that might have been created by tiny lifeforms billions of years ago.
Nicknamed 'Cheyava Falls', it was found on July 21 as Perseverance explored an old river valley called Neretva Vallis in Mars' Jezero crater.
The coffee table-sized rock, about 1m by 60cm, has some intriguing features. Nasa scientists found traces of organic material, strange spots similar to fossilised microbes on Earth and signs that water once flowed through it.
Nasa says these clues hint at the possibility of ancient Martian life, but cautions that more research is needed to be certain.
Ken Farley, the project scientist for the mission at the California Institute of Technology, described Cheyava Falls as "the most puzzling, complex and potentially important rock yet investigated by Perseverance".
However, the research team stressed that non-biological processes could also be responsible for the observed features.
“On the one hand, we have our first compelling detection of organic material, distinctive colourful spotsindicative of chemical reactions that microbial life could use as an energy source, and clear evidence that water, necessary for life, once passed through the rock,” Farley said.
“On the other hand, we have been unable to determine exactly how the rock formed and to whatextent nearby rocks may have heated Cheyava Falls and contributed to these features.”
The discovery of Cheyava Falls adds to evidence that Mars was once a warmer, wetter planet potentially capable of supporting life.
Researchers believe that if life ever evolved there, traces should remain within its rocks.
Scans by Perseverance's Sherloc instrument suggest the rock contains organic compounds - carbon-based molecules considered building blocks of life, though these can also form through non-biologicalprocesses.
The rock features large white veins of calcium phosphate alongside reddish bands, likely haematite. Closer inspection revealed dozens of small, leopard-like spots, each surrounded by a black ring containingiron and phosphate.
David Flannery, an astrobiologist at Queensland University of Technology and mission member, called these spots "a big surprise", noting that on Earth, similar features "are often associated with the fossilised record of microbes".
Prof John Bridges from the University of Leicester emphasised the importance of the discovery. He said: "This is what Mars Sample Return is all about.
“We have never seen anything like this from Mars before, not in our Martian meteorite collections, not with Mars Science Laboratory or other landers."
He added: "The reality is we need to get these samples back on Earth to do the detailed electron microscopy and isotope analyses to check if these formed with ancient microbial action orabiotically."
Prof Charles Cockell, an astrobiologist at the University of Edinburgh, said: "Although these features don't provide unambiguous evidence of life, they do confirm that Mars was a very dynamic planet with all the ingredients for life, including organic carbon."
He added: "We need to bring back samples, or in my view, even better, send humans, to find if we are seeing the signatures of life."
