Blue-green algae

Cyanobacteria (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 "cyanobacteria" comes from the colour of the bacteria, cyan; the bacteria do not use or produce cyanide whose chemical prefix is cyano-.
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Noun
1. predominantly photosynthetic prokaryotic organisms containing a blue pigment in addition to chlorophyll; occur singly or in colonies in diverse habitats; important as phytoplankton
(synonym) cyanobacteria
(hypernym) eubacteria, eubacterium, true bacteria
(hyponym) nostoc
(member-holonym) class Cyanobacteria, Cyanophyceae, class Cyanophyceae