mollusc vs weakness

mollusc

noun
  • A weak-willed person. 

  • A soft-bodied invertebrate of the phylum Mollusca, typically with a hard shell of one or more pieces. 

weakness

noun
  • The condition of being weak. 

  • An inadequate quality; fault 

  • A special fondness or desire. 

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