Chert of the middle Precambrian Gunflint Iron-Formation (ca. 1.9 b.y. old) from near Schreiber, Ontario, Canada, has yielded some of the oldest well preserved cellular remains yet known. Observation of the spherical unicellular forms has indicated two methods of reproduction: some evidently reproduced by fission, others of similar morphology, by budding. The latter process is not known to occur in blue-green algae, the taxon to which the unicellular forms often have been assigned.
Perhaps the most interesting possibilities for their biological affinities are that the unicellular forms are all procaryotic blue-green algae that were capable of different reproductive methods or that those unicellular forms which bud are eucaryotic fungi.