Description of Ciliophrys infusionum
, in the heliozoan stage the cells are about 4 - 9 microns across, and have a central nucleus and one flagellum held in a figure of eight. The cells are spherical with delicate pseudopodia extending radially from the body and bearing extrusomes. The cells may change from the heliozoan stage with pseudopodia and a slow beating flagellum to a swimming flagellate without pseudopodia and with the flagellum beating rapidly. In swimming cells, the nucleus is located apically. Observed to consume suspended bacteria. When feeding, bacteria adhere to the pseudopodia and then are drawn to the body. The cells eat diatoms up to 18 microns long.