[2] The genus name is derived from Greek and means "spindle-shaped" or "arrow-shaped",[3] and refers to the shape of the cells.

They are usually spindle-shaped, with two sharply pointed ends, but sometimes may develop three- or four-pointed cells.

In asexual reproduction, zoospores develop from vegetative cells, or less commonly aplanospores.

[5] The resulting zygotes from fertilization are initially surrounded by a thin membrane, later developing a thick wall and often an orange-red color.

[4] It occurs in shallow, temporary freshwater pools, and has been recorded from California, Texas, Australia, Namibia,[1] and Hungary.