Unique stromatolites at Hamelin Pool, Western Australia

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I have always thought Western Australia was pretty special and this was reinforced when we visited Hamelin Pool in the Shark Bay area of our state. As well as have a shell beach, Hamelin Pool is one of only a very few places where there are living stromatolites. There is another colony in the Bahamas and smaller collections elsewhere. These are pretty underwhelming to look at, in appearance being something of a cross between huge cauliflowers and rocks. Stromatolites (from the Greek for ‘layered rock’) are microbial reefs and are one of the earliest known life forms, so are effectively living fossils. The deposits are created by cyanobacteria and formed by the trapping, binding and cementation of sedimentary particles. The stromatolites release oxygen into the air and can sometimes be seen fizzing underwater. The salinity of Hamelin Pool is almost twice that of the ocean and ultraviolet radiation is extreme, meaning there are few predators so the microbial mat communities thrive. I wondered what could possibly be a predator but apparently there is a gastropod (saltwater snail) that can destroy the stromatolites. Growth is incredibly slow with perhaps 1mm per year being added to the surface of the rocks. There is a nicely made boardwalk which allows you to view the stromatolites without the risk of damaging them.