Stromatolites By Matt Young August 13, 2009 12:00 MST Photograph by James Kocher. Photography contest, finalist in the “Minerals” category. Stromatolites – Fossilized colonies of filamentary cyanobacteria (blue-green algae) and other microbes. Gunflint formation, approximately 1.9 billion years old. Microscopic fossils are sheaths and external cellular secretions/coverings very much like modern cyanobacteria, which may be survivors from Gunflint time. Whitefish River, Lybster Township, Ontario, August, 1992.