any of a genus (Chlorella) of microscopic, unicellular, green algae with spherical cells: several species are rich sources of proteins, carbohydrates, and fats
See chlorella in American Heritage Dictionary 4
(klə-rĕlˈə)
noun
Any of various unicellular green algae of the genus Chlorella, easily cultured and often used in studies of photosynthesis and other experiments.