bag of shells vs flyspeck

bag of shells

noun
  • A trifle. 

  • Used other than figuratively or idiomatically: see bag, shell. 

flyspeck

noun
  • Anything tiny or insignificant. 

  • Housefly excrement, visible as a minuscule black dot. 

verb
  • To inspect in minute detail to ensure that something contains no flaws; nitpick. 

  • To bespeckle with tiny spatters of color. 

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