Genus Paulinella Lauterborn, 1895
Diagnosis: shell pyroid or broad-elliptical, not compressed, composed of siliceous, rectanguloid plates with slightly rounded, scarcely overlapping borders, arranged in circumferential longitudinal rows; in apertural view the plates form a counter-clockwise spiral, with one pentagonal scale at the aboral pole. Pseudostome small. Cell with usually two sausage-like organelles: endosymbionts of cyanobacterial origin. Filopodia, usually fast moving.