bivalve vs seashell

bivalve

noun
  • Any mollusc belonging to the taxonomic class Bivalvia, characterized by a shell consisting of two hinged sections, such as a scallop, clam, mussel or oyster. 

  • A pericarp in which the seed case opens or splits into two parts or valves. 

seashell

noun
  • The empty shell of a marine mollusk. 

  • A very light pink colour, like that of some seashells. 

adj
  • Of a very light pink colour, like that of some seashell. 

How often have the words bivalve and seashell occurred in a corpus of books? (source: Google Ngram Viewer )