Stromatolites

Stromatolites

Some of the earliest life on Earth dates back 3.5 million years, and fossilised stromatolites in ancient rocks are evidence of primitive blue-green algae. Descendants of these ancient life forms can still be seen today in places like the shallow, sunlit waters of Shark Bay in Western Australia. Evaporation makes the water there too salty for snails and other marine creatures that would eat the blue-green algae, so they thrive and grow, trapping sediment and forming the large rocky lumps known as "stromatolites". [CH] {EN}