Mesoproterozoic Baicalia Stromatolites from China

Here is very interesting and pretty mid-Proterozoic stromatolite from near Beijing, Peoples Republic of China. The oval to circular, darker reddish-brown structures in the matrix are bacterial fossil nodules, referred to as Baicalia sp. These may be what are commonly called algal balls, formed by separate colonies of prokaryotic, photosynthetic bacterial, e.g., likely to be cyanobacteria, the primitive organisms that largely produced Earth's atmospheric oxygen. The colonies grow as a sphere of increasing radius. The distinct structures within the stromatolite could signify temporal variation of growth patterns in a large global colony that resulted due to changing conditions in the benthic environment.

The beautiful specimen has been polished to a mirror finish perpendicular to the colonies on the side shown.

Baicalia sp. is a putative bacteria believed to have been photosynthetic prokaryotes that oxidized ambient iron and other heavy metals as part of their metabolism pathways. The presence of the metals iron for precipitation would be tangible evidence that Precambrian times had extensive volcanic activity.