carapace vs rind

carapace

noun
  • in figurative use 

  • A hard protective covering of bone or chitin, especially one which covers the dorsal portion of an animal. 

rind

noun
  • The gall, the crust, the insolence; often as "the immortal rind" 

  • tree bark 

  • A hard, tough outer layer, particularly on food such as fruit, cheese, etc 

  • An iron support fitting used on the upper millstone of a grist mill. 

verb
  • To remove the rind from. 

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