alga vs moss

alga

noun
  • Any of many aquatic photosynthetic organisms, including the seaweeds, whose size ranges from a single cell to giant kelps and whose biochemistry and forms are very diverse, some being eukaryotic. 

moss

noun
  • Any alga, lichen, bryophyte, or other plant of seemingly simple structure. 

  • Any of various small, green, seedless plants growing on the ground or on the surfaces of trees, stones, etc.; now specifically, a plant of the phylum Bryophyta (formerly division Musci). 

  • A bog; a fen. 

  • A kind or species of such plants. 

verb
  • To become covered with moss. 

  • To cover (something) with moss. 

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