from culture

Description:

Proterospongia (pro-terr-ow-sponge-ee-a) a collar flagellate (choanoflagellate), normally regarded as forming flat colonised, but in culture the capacity to form colonies can be lost, to leave cells indistinguishable from the solitary Monosiga. With apical flagellum and a collar, only the edge of which is seen as a dark line on either side of the flagellum. Phase contrast.