FOSSILS of the earliest known life on Earth have been discovered, according to a new study.

The mind-blowing 3.5billion-year-old fossils were found in the Australian desert but experts have struggled to confirm their identity until now.

The ancient fossilised microbe formations are called stromatolites and have finally been shown to contain traces of organic matter.

Geologist Raphael Baumgartner from the University of New South Wales (UNSW) in Australia explained: "This is an exciting discovery - for the first time, we're able to show the world that these stromatolites are definitive evidence for the earliest life on Earth."

Searching for fossilised microbes is so difficult because it's hard to tell whether you're looking at fossilised microbe formations or just natural folds in the rock.

The fossils in question were discovered at the Dresser Formation fossil site of the Pilbara region in Australia back in the 1980s.

2 The rock formations contained organic matter, which indicates that small living microbes made them Credit: Baumgartner et al / Geology

However, without modern technologies it was hard to prove the fossils weren't just plain old rocks.

A recent study in Greenland wrongly claimed to have found 3.7billion-year-old fossils, which turned out to just be rock creases.

The Australian study is different because it has definite evidence of organic matter to back it up as something must have been living in the rocks to produce it.

Baumgartner said: "The organic matter that we found preserved within pyrite of the stromatolites is exciting - we're looking at exceptionally preserved coherent filaments and strands that are typically remains of microbial biofilms.

"I was pretty surprised - we never expected to find this level of evidence before I started this project."

Perhaps the most exciting thing about the ancient microbe fossils is that they could point us to evidence of life on Mars.

This is because the deposits in the region of Australian desert in question are the same age as the crust of Mars.

Nasa has been investigating the Pilbara region to try and learn more about the geological signatures that could pinpoint the presence of stromatolites on the red planet.

It is likely that the fossilised organisms found lived in hot springs when they were alive and Mars does show evidence of its own ancient hot springs.

Signs that the organisms once lived include air bubbles created by the gases that they produced.

2 It can be difficult to tell whether stromatolite rock structures like this one were made by organisms or just occurred naturally Credit: Getty - Contributor

Baumgartner concluded: "Understanding where life could have emerged is really important in order to understand our ancestry.

"And from there, it could help us understand where else life could have occurred – for example, where it was kick-started on other planets."

This research has been published in the journal Geology.

A timeline of life on Earth The history of the planet in years... 4.6billion years ago – the origin of Earth

3.8billion years ago – first life appears on Earth

2.1billion years ago – lifeforms made up of multiple cells evolve

1.5billion years ago – eukaryotes, which are cells that contain a nucleus inside of their membranes, emerge

550million years ago – first arthropods evolve

530million years ago – first fish appear

470million years ago – first land plants appear

380million years ago – forests emerge on Earth

370million years ago – first amphibians emerge from the water onto land

320million years ago – earliest reptiles evolve

230million years ago – dinosaurs evolve

200million years ago – mammals appear

150million years ago – earliest birds evolve

130million years ago – first flowering plants

100million years ago – earliest bees

55million years ago – hares and rabbits appear

30million years ago – first cats evolve

20million years ago – great apes evolve

7million years ago –first human ancestors appear

2million years ago – Homo erectus appears

300,000 years ago – Homo sapiens evolves

50,000 years ago – Eurasia and Oceania colonised

40,000 years ago – Neandethal extinction

Forest floor captured 'BREATHING'

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In other archaeology news, the world's 'first' bottles used to feed babies animal milk have been discovered.

An ancient mass grave filled with the battered bodies of 26 adults and children may be evidence of the world's 'first war crime'.

And, new research suggests Neanderthals may have been wiped out by a common childhood illness.

What do you make of this early life discovery? Let us know in the comments...

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