Scientists have discovered possibly the earliest signs of life on Earth - remains of bacteria that are almost three-and-a-half billion years old - in a remote region of northwest Australia.
Evidence of the complex microbial ecosystem was found in sedimentary rocks in the remote Pilbara region in Western Australia, an area which contains some of the world's oldest rock formations.
One of the researchers, David Wacey, from the University of Western Australia, said the newly-discovered evidence of bacteria "was possibly the oldest signs of life on Earth".
"There was plenty of life from the 3.4- and 3.43-billion-year-old mark - this is pushing it further back," he told the Telegraph.
"There are slightly older claims of life in rocks in Greenland - but the rocks there have been so deformed that it is very difficult to tell if what you are seeing was actually there in the first place. With these microbial systems in the Pilbara, you can see these things in the field and under the microscope.
You can see how the bacteria were interacting with the sediment they were living on."
Professor Wacey said it was no longer possible to see the actual cells, but the scientists had discovered the marks left behind by large clusters, or mats, of microbes. The traces were discovered in a body of rock called the Dresser Foundation, near Port Hedland.
"We don't see the microbe themselves but we see large scale structures that the microbes constructed before they died," he said. "We see tufts and wrinkles and - when we look down the microscope - we see filaments tangled in sand grains. We are also seeing organic material which are the actual microbes but they are decomposed to the point that we cannot see a cell. You just see a mass of carbon-rich material."
The team of scientists believe that the findings may help with the search for life on other planets.
"There are applications for searching for life elsewhere and knowing what to look for," Professor Wacey said. The findings have been published in the journal Astrobiology.