nacre vs seashell

nacre

noun
  • A pearly substance which lines the interior of many shells; mother-of-pearl. 

seashell

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

  • The empty shell of a marine mollusk. 

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

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