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Got the itch to collect and study some stromatolites, so I did some searching and feel that I successfully scratched the itch. I found a section of the Cambrian Copper Ridge dolomite that exposes a plethora of stromatolites of various morphologies. Many of them look as if they are straight out of Shark Bay in Australia, with the characteristic domal structure attached to a thinner holdfast on a hard substrate. Stromatolites are formed over a long period of time in tidal zones by colonies of photosynthetic bacteria and/or algae that form sticky layers that trap sediments and concrete them into layers. The colony then grows over the older, cemented colony and the cycle repeats itself. The process is obviously a lot more complicated than that, but I digress. Stromatolites are the oldest confirmed fossils to have been discovered, with the current oldest ones to be confirmed coming from the Strelley Pool Chert formation in Western Australia, dating back to the early Archaen at approximately 3.4 billion years ago. At that point in time, the Earth's atmosphere was largely devoid of oxygen, primarily being composed of CO2. Over the next several billion years, these stromatolites were largely responsible for oxygenating the atmosphere. They may not look like much, but these bacterial colonies were extremely important to creating Earth's biosphere. After the Cambrian explosion, stromatolites began to become quite rare in the fossil record, with multicelluar organisms feeding on them and disrupting the cementation process. After that point and to this day, stromatolites primarily thrive in extreme environments were the animals that feed on them cannot survive. The stromatolites in the Shark Bay, Australia area live in a hypersaline environment created by a seagrass barrier just off the coast. Unfortunately climate-change induced increases in precipitation are causing floods that reduce the salinity of this location and threaten the survival of the stromatolite colonies. With that information, enjoy these photos of stromatolites. Cube scale is 2cm on each side Large domal type in the position it would have grown in: Another domal type, almost spherical in shape, composed of multiple separate colonies that appear to have fused together: Another domal type: Cross section of broken laminar piece showing growth layers over an oolitic limestone substrate: A different one, I hope to polish this face: Layers under microscope: