Stromatolites growing in the shallow, saline waters of Shark Bay, Western Australia. Those here have been exposed by a low tide.


Stromatolites are formed when cyanobacteria grow and cement together carbonate precipitates and sand grains.


Cyanobacteria are the most ancient know organisms on the earth. Stromatolites preserved in the geological strata provide the oldest know record of living organisms on earth (3.5 billion years)


Photo, October 2005