Assertion: whelk's shell | /r/HasProperty | hard
Facets:
Source sentences:
text: The whelk builds the hard shell from calcium carbonate that it extracts from the seas.
text: A shell is a hard outer layer, which has evolved in a very wide variety of different animals, including molluscs, sea urchins, crustaceans, turtles and tortoises, and armadillos.