Assertion: mollusk's shell | /r/HasProperty | cuttlebone
Facets:
Source sentences:
text: However, all molluscan shells are formed from the ectoderm (outer layer of the embryo); in cuttlefish (Sepia spp.), for example, an invagination of the ectoderm forms during the embryonic period, resulting in a shell (cuttlebone) that is internal in the adult.