Hamelin Bay, Western Australia by Hilke Maunder

800 kilometres north of Perth, the capital of Western Australia, a man-high brick wall appears in the middle of the endless expanse of low bushland. "Shark Bay - World Heritage Area" welcomes visitors. What at first glance appears to be an endless wasteland of scrub, red sand and overgrown shores has been under UNESCO protection since 1992: the elongated bay of Shark Bay with the Peron Peninsula and offshore islands on the 26th parallel of Western Australia.
The uniqueness of this World Heritage Site can be seen at Hamelin Pool, at first glance a bay with a wooden jetty and grey-black rocks in the shallow waters. A quick glance and most of the visitors disappear. I stayed and studied the information board But it gets exciting when you study the information boards more closely. Descendants of the world's first living creatures created these formations 3.5 billion years ago - single-celled, blue-green algae without a cell nucleus. These simple cyanobacteria succeeded in creating complex organic compounds from the primordial soup of the oceans. Their building blocks: the water, the carbohydrates dissolved in it and the light of the sun. Their product: a biomass from which all other life emerged - rock-like towers, black, spongy mats and hump-like layered rocks.
However, the waste product of their intensive activity, which plants continue today as photosynthesis, dealt them the death blow: oxygen. Their two million years of production had changed the Earth's atmosphere: from oxygen-free to oxygen-rich, from reducing to oxidising. A climate change that killed the stromatolites. As fossilised rocks, they are a reminder of the global environmental catastrophe of prehistoric times.