Stromatolites are layered mounds or sheet-like layers of sedimentary rock that were originally forced by growing on a layer of cyanobacteria, a single-cell microbe. Fossilized stromatolites provide a record of ancient life and tidal patterns on Earth.
Millions of years ago, seas all over the world would resemble the picture above, which was taken from Shark Bay, Australia. This unique pattern was created through a process of accumulation of calcium carbonate and the depletion of carbon dioxide in the water.
Cyanobacteria, which resulted in the creation of stromatolites, were one of the first organisms on Earth. Certain kinds of cyanobacteria are 3.7 billion years old. They produced oxygen as a by-product of photosynthesis, which made it possible for more complex life forms to evolve in our oceans.