SOME of the earliest microbes may have been able to move around under their own power using whip-like "tails", according to a study of fossils from 3.4 billion years ago. But other palaeontologists say the evidence is weak, although it is possible that the ability to move did evolve early in life's history. The oldest confirmed fossils are 3.5 billion years old. They are all single-celled bacteria-like organisms. Researchers led by Frederic Delarue at Sorbonne University in Paris, France, have now described a new collection of microfossils from 3.4-billion-year-old rocks in the Strelley Pool Formation of Western Australia. The leaf-shaped cells are 30 to 84 micrometres long, and about half as wide. Some "microfossils" turn out to be inorganic rock formations, so the team performed chemical tests to confirm they are the remains of living organisms. "We observe nitrogen and phosphorus that are preserved in the fossils," says team member Romain Tartese at the University of Manchester in the UK - both of these are characteristic elements of life.
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