1 One of the algal cells in the thallus of a lichen.
2 A motile, single cell released by filamentous bacteria of the family Leucotrichaceae.
3 A non-motile spore released by some cyanobacteria.
4 In some green algae (Chlorophyta), a vegetative cell that enlarges and undergoes division. In Volvox it may be suspended in the hollow interior of the sphere.