cryptocyst

cryptocyst (noun; Greek kryptos, hidden; kystis, bladder): (Bryozoa: Gymnolaemata) 1. One of the two basic wall morphologies of bryozoans consisting of wholly interior walls, leaving a superficial hypostegal coelom uniting contiguous zooids

See also: gymnocyst. 2. A calcareous plate that functions as a hydrostatic organ in Cheilostomata.