These have been recently reclassified as Maastrictian stage (Cretaceous). For many years they were classified as Precambrian. To keep up with the latest research and scientific progress, I've updated this section. Original scientific papers claiming they were Precambrian are now superseded by the latest information. Cut and Polished Slices of Precambrian Stromatolites from South America. Stromatolites are one of the earliest fossilized forms of life to be found. They are the result of the building process of sediments and cementations in shallow waters of cyanobacteria, or blue-green algae's. These can be cut to display the layers that have been built up over years and years, in the same way a tree is cut to show its growth rings. Seasonal changes may have slowed down growth or totally the opposite and this can be seen in the varying thickness of layers and different mineral content of each layer over time. Stromatolites can still be found today in places such as Shark Bay in Australia.
The specimens you see below all come from the Maastrichtian El Molino Formation, S. Cochabamba, Bolivia, S. America. These are colonial Stromatolites. They are dated to 70 Million years old. They are still incredibly old.
Best Grade Cut and Polished Stromatolite Slices from Bolivia
Australian/South Africa Stromatolites Precambrian age Tiger Iron Stromatolites from Western Australia. Banded Iron hematite replaced colonial Stromatolites. These are highly polished top grade specimens. They look amazing in real life far better than any picture can show!