Some of these stromatolites can be up to a meter in diameter.

Stomatolites

Stromatolites are trace fossils of the biofilms of blue-green algae that grow around an object such as a shell or oyster. As the algal filaments grow outwards, sediment is continually deposited and accreted onto the surface of the algal mat. The stromatolite increases in size and forms distinctive concentric rings if you break the stromatolite in cross section.

This is an earlier stage of stromatolite development that is growing around half of an inch long bivalve.
This is an earlier stage of stromatolite development that is growing around half of an inch long bivalve.

The outer surface of the fossil stromatolites look quite knobbled in their appearance. These round boulders can sometimes be quite large in the fossil record at Lake Turkana, sometimes reaching a meter wide.

Some of these stromatolites can be up to a meter in diameter.
Some of these stromatolites can be up to a meter in diameter.

Stromatolites grow in shallow, hypersaline pools in shore settings, inhospitable to molluscs and other invertebrates that might otherwise graze on the algae. There are no modern examples of stromatolites found today at Lake Turkana, however there are modern marine stromatolites that are in lagoons in Shark Bay in Australia. A 3D model of a stromatolite from 0.7 million year deposits at Lake Turkana can be seen here;

This is a cross section of a stromatolite that has grown up around an oyster shell.
This is a cross section of a stromatolite that has grown up around an oyster shell.

 

2 thoughts on “Stomatolites”

    1. There is some variability. Sometime the texture of the surface is a little more pitted and they can be stained darker. We’ll add some more examples as they are discovered in our pictures

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