Unicells that typically excrete mucopolysaccharides and form colonies are treated as Cyanobacterial colonies in Phycokey. Some predominantly unicellular genera do occasionally secrete enough mucilage to form 'loose' connections among a few cells, e.g. Synechocystis. Others retain endospores and exospores within a sheath, e.g. Stichosiphon, giving the appearance of multicellularity.