Billion-year-old fossils found in the Pilbara are not fossils at all, new analysis from the University of WA has found.
The supposed microfossils were discovered near Marble Bar in 1993 by US scientist Bill Schopf and at 3.46 billion years old were thought to be earth's oldest microfossils.
This discovery was widely distributed by textbooks, museums and online reference guides as the earliest evidence of life on earth, even going so far as to rebut the case against microfossils in a Martian meteorite in 1996.
Now a study led by UWA researchers David Wacey and Martin Saunders has rained on the Pilbara's parade by disproving the region's claim to be home to the earliest signs of life because Mr Schopf's discoveries were mineral deposits, not fossils.
Mr Wacey said on studying the pseudofossils at a high spatial resolution, they lacked evidence for coherent rounded cell walls needed to be classified as microfossils.
"A false appearance of cellular compartments is given by multiple plates of clay minerals having a chemistry entirely compatible with a high temperature hydrothermal setting," he said.
"We studied a range of authentic microfossils using the same transmission electron microscopy technique and in all cases these reveal coherent, rounded envelopes of carbon having dimensions consistent with their origin from cell walls and sheaths.
"(The pseudofossils) have a complex, incoherent, spiky morphology, evidently formed by filaments of clay crystals coated with iron and carbon."
The research was co-written by the late Oxford University Professor Martin Brasier, who was an early critic of Mr Schopf's discovery.
Before his death, Professor Brasier said the research would provide a closing chapter for the apex microfossil debate. He said he hoped books and websites would now focus on more recent, robust microfossil discoveries in WA.