StromatolitesArticle | Updated 7 years ago Stromatolite specimen WA Museum This is part of a stromatolite and represents some of the oldest evidence of life on Earth. It’s a little under 3.5 billion years old! Stromatolite specimen Image copyright WA Museum Stromatolites form in shallow water; some of the ancient ones from Western Australia formed along the rim of exploded volcanoes. This specimen was collected in the northern Pilbara by a former PhD student at The University of Western Australia, and is now part of the WA Museum’s Department of Earth and Planetary Sciences collection. Some evidence suggests early stromatolites may not have been formed largely by photosynthesising cyanobacteria because there’s not much evidence of dissolved oxygen in the oceans at this time. To put this in perspective: you may think the iron ore we mine in the Pilbara today is old. Well, the banded iron formation from which ore is mined didn’t start forming until there was enough dissolved oxygen reacting with free iron in the oceans – and that was several hundred million years after this stromatolite was formed.