zo·o·chlor·el·la 
(zō′ə-klə-rĕlə)
(zō′ə-klə-rĕlə)n. pl. zo·o·chlor·el·lae (-klə-rĕlē)
Any of various one-celled green algae that live symbiotically within the cells of aquatic invertebrate organisms such as sponges and sea anemones or within certain protists.