Collenia Temporal range: 2400–2100 Ma Pha. Proterozoic Archean Had. Precambrian
Section of Collenia undosa stromatolite from 2110 million year old banded iron formation, Biwabik
Collenia undosa stromatolite from Precambrian of United States
Scientific classification
Domain:	Bacteria
Phylum:	Cyanobacteria
Family:	Spongiostromata
Subfamily:	Stromatolithi
Genus:	Collenia Walcott, 1914[1]
Species
C. frequens C. symmetrica C. undosa

Collenia is genus of fossil cyanobacteria that form a particular type of stromatolites.^[2]

Description

Collenia are stromatolites made up of convex layers flattened in the center, forming columnar colonies. The microorganisms involved were likely photosynthetic bacteria expiring oxygen.^[3]

Fossil record

Collenia stromatolites were very common in the late Precambrian, about 2.2 to 2.4 billion years ago.