A team of Australian and British geologists have discovered fossilized single-celled organisms that are 3.4 billion years old, making them the oldest fossils ever discovered. The finding reveals that life evolved on earth very soon following the "Late Heavy Bombardment," in which waves of asteroids slammed into earth's earliest formation. The new microfossils are described in Sunday’s issue of Nature Geoscience by a team led by David Wacey of the University of Western Australia and Martin D. Brasier of the University of Oxford. The fossils were found in the Strelley Pool rock formation in Western Australia, embedded in a layer of sandstone. The discovery also adds to the ongoing struggle over who has found the world's oldest mircofossils.