man of straw vs mollusc

man of straw

noun
  • A weak person. 

  • A person put in the front of some business, but who is not really responsible. 

  • One who is financially irresponsible. 

  • A tactic used in debates and arguments where a weaker thesis is substituted for the opponent's real proposition, this thesis then being refuted, thereby creating the illusion of winning the argument against the original proposition. 

mollusc

noun
  • A weak-willed person. 

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

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