cystid

from The Century Dictionary.

• noun In Polyzoa: The saccular, planuliform, ciliated embryo, from one end of which one or more polypids are developed from thickenings of the wall of the sac.
• noun The cell in which the body of the mature individual is contained, as distinguished from the polypid itself.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Zoöl.) One of the Cystidea.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun zoology One of the Cystidea.