Phylum Cyanobacteria, Lichens and Fungi
Cyanobacteria produce oxygen as a byproduct of photosynthesis. Although they are known as Blue-green algae, they are in fact not an algae because their cells do not have a nucleus.
Marine Lichens are organisms made up of a fungus and a cyanobacteria that exist in a symbiotic relationship.
The photos below are pictures of organisms that I believe fall into one of these two categories