It's difficult to track down the oldest traces of life. The rock you end up with is going to look a lot like an ancient life form.

Even though debates are not always settled, it takes a real eye to distinguish between the two.

There are rock formations from Western Australia that are over 3 billion years old. It's not easy to rule out the possibility that the stromatolites are simply geological.

A new analysis by an international team of researchers shows that these formations are biological in origin.

"If an archaeologist discovers the foundations of a ruined city, they would know it was built by people because it would bear all the hallmarks of being built by people," says Keyron Hickman-Lewis of the Natural History Museum.

Stromatolites have many structural elements that allow us to understand their processes of formation and origin. We can be archaeologists very soon.

Around the world, stromatolites are found. They consist of laminated, or finely layers, rock that could be produced either by a chemical reaction between the rock and its environment or by a mineral deposition.

The job of the paleontologist is to try to figure out which is which, as seen in the 3.8 billion-year-old stromatolite-like layers in Greenland, which were first declared the world's oldest fossils and then found to be just plain old rocks.

The identification of the oldest fossils on this marvelous, 4.54 billion–year old blue marble of ours isn't just an exercise in breaking records. The ancient origins of humanity and the life that thrives today are important to all of us.

The oldest known traces of life on Earth are the stromatolites from the Strelley Pool formation. The Western Australian Dresser Formation contains 3.48 billion-year-old stromatolites.

They used a variety of techniques to look at the two- and three-dimensional stromatolites.

The structures and characteristics shown in the tests are consistent with a biological origin.

Dresser Formation stromatolite sample showing clear lamination and dome structures. (Hickman-Lewis et al., Geology, 2022)

The team concluded that once upon a time, the stromatolites were mats ofbacteria. The dome structures resembling the cups in an egg carton were formed when the microbes pushed up away from the soil and towards the sun. The shapes were found in the fossil formation.

The pattern of rock known to be created by the growth of microbes was observed by the team. The dome structures were likely the result of organisms moving towards the sun. There are small voids in the rock.

These clues make them the oldest evidence of life on Earth and have implications for the search for life elsewhere.

The Jezero crater on Mars may have been a very similar environment when the Dresser Formation was shallow. There is a chance that life was emerging on Mars at the same time as the Noachian. If the Perseverance rover finds fossils on Mars, it will be possible to identify fossils on Earth.

Stromatolites are the oldest direct evidence for life on Earth, according to the researchers.

The paleodepositional setting, poly Extremophilic biology, and taphonomy make them ideal analog biosignatures for Mars.

The research has appeared in a journal.