<unk>  (Greek: κυανόs (kyanós) = blue + bacterium) also known as Cyanophyta is a phylum (or "division") of Bacteria that obtain their energy through photosynthesis. They are often referred to as blue-green algae, although they are in fact prokaryotes, not algae. The description is primarily used to reflect their appearance and ecological role rather than their evolutionary lineage. The name<unk> " comes from the colour of the bacteria, cyan; the bacteria do not use or produce cyanide whose chemical prefix is cyano-.
Putative fossil traces of<unk>  have been found from around 3.8 billion years ago (b.y.a.). See: Stromatolite. They are a significant component of the marine nitrogen cycle and an important primary producer in many areas of the ocean. Their ability to perform oxygenic (plant-like) photosynthesis is thought to have converted the early reducing atmosphere into an oxidizing one, which dramatically changed the life forms on Earth and provoked an explosion of biodiversity. See: Oxygen Catastrophe.
Cyanobacteria
Bacillus
Coccus
Chlamydiae
Amoebozoa
Proteobacteria
Nontuberculous mycobacteria
Microorganism