Zooid

A zooid or zoöid /ˈzoʊ.ɔɪd/ is a single animal that is part of a colonial animal. The zooids can either be directly connected by tissue (e.g. corals, Catenulida, Siphonophorae or Ectoprocta) or share a common exoskeleton (e.g. Bryozoa or Pterobranchia). The colonial organism as a whole is called a zoon /ˈzoʊ.ɒn/, plural zoa.