Assertion: snail's operculum | /r/HasProperty | door-like part
Facets:
Source sentences:
text: Snails protect themselves from predators by taking coverage beneath their shells and through the use of the operculum, a door-like part that closes the opening of the shell.
text: In life, when the soft parts of these snail are retracted, in some groups the aperture of the shell is closed by using a horny or calcareous operculum, a door-like structure which is secreted by, and attached to, the upper surface of the posterior part of the foot.