C values indicate biogenicity in rocks from West Greenland.
3.4 Ga. They are quite small, generally less tham 10 microns. Cyanobacteria are O 2 -producing photosynthetic autotrophes. Photos of some common cyanobacterial genera. More photos of cyanobacteria from Purdue University. These cells are preserved in colonies, populations of cells, that inhabited intertidal and shallow water carbonate-rich environments, forming laminated mats.