Noun
A disk which surrounds the mouth and bears the tentacles of the Bryozoa. See Phylactolemata.
Source: Webster's dictionaryIn some species the retracted invert and lophophore are protected by an operculum ("lid"), which is closed by muscles and opened by fluid pressure. Source: Internet
On the other hand, the founding polyp of a coral has a shape like that of its daughter polyps, and coral zooids have no coelom or lophophore. Source: Internet
Sensors at the tips of the tentacles may check for signs of danger before the invert and lophophore are fully extended. Source: Internet