sea cradle vs mollusc

sea cradle and mollusc both are nouns.

Word	Noun	Adjective	Verb	Adverb
sea cradle	Yes	No	No	No
mollusc	Yes	No	No	No

As nouns, mollusc is a hypernym of sea cradle; that is, mollusc is a word with a broader meaning than sea cradle:

sea cradle: primitive elongated bilaterally symmetrical marine mollusk having a mantle covered with eight calcareous plates
mollusc: invertebrate having a soft unsegmented body usually enclosed in a shell

Other hypernyms of sea cradle include mollusk, shellfish.

sea cradle (noun)	mollusc (noun)
primitive elongated bilaterally symmetrical marine mollusk having a mantle covered with eight calcareous plates	invertebrate having a soft unsegmented body usually enclosed in a shell