ooid vs ovoid

ooid

adj
  • Shaped like an egg; ovoid; ovate. 

noun
  • A small calcium carbonate or iron coated grain found on the seafloor. 

ovoid

adj
  • Egg-shaped; shaped like an oval, but more tapered at one end; ovate. 

  • Shaped like an oval. 

noun
  • Something that is oval in shape. 

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