penfish vs rachis

penfish

noun
  • A squid. 

  • Any of various porgies of the genus Calamus 

rachis

noun
  • An anatomical shaft or axis in a marine invertebrate. 

  • The main shaft of either a compound leaf, head of grain, or fern frond. 

  • The central shaft of a feather. 

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