Noun
any of the flagellated cells in sponges having a collar of cytoplasm around the flagellum; they maintain a flow of water through the body
Source: WordNetFor example, sclerosponges ("hard sponges") have massive calcium carbonate exoskeletons over which the organic matter forms a thin layer with choanocyte chambers in pits in the mineral. Source: Internet
The single-celled choanoflagellates resemble the choanocyte cells of sponges which are used to drive their water flow systems and capture most of their food. Source: Internet