alga

/ˈæl.ɡə/

IPA: /AE1 L G AH0/

noun
  1. 1

    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.

Source: https://en.wiktionary.org/wiki/alga