sessile vs unmovable

sessile

adj
  • Permanently attached to a substrate; not free to move about. 

  • Attached directly by the base; not having an intervening stalk; stalkless. 

unmovable

adj
  • Not physically able to be moved. 

  • Incapable of being emotionally moved or persuaded. 

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