Description
Stromatolites Are the oldest fossils known to man. There are some specimens in Australia dated to 3.9 billion years old! The cyanobacteria that created these fossils photosynthesised carbon dioxide and produced oxygen. At this time in the earth's history carbon dioxide was abundant but there was very little oxygen. For over 2 thousand million years trillions of cyanobacteria produced oxygen and eventually the earth's atmosphere reached about 20% oxygen.
Stromatolites are created when thick mats of cyanobacteria collected sand and other sediments. As the sediments grew a layer covering the cyanobacteria the bacteria also grew through the sediments forming many layers apparent in these fossils.
While we speak of cyanobacteria as a single thing stromatolites are actually a colony of many different bacteria living in symbiosis.
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