Unicellular Micrasterias cells are green freshwater algae filled with chlorophyl that help form the bottom of the food chain throughout much of the world. Micrasterias displays a bilateral symmetry with two mirror image semi_cells joined by a narrow isthmus containing the nucleus of the organism. This dual semi_cell structure is unique to the group of green algae to which Micrasterias belongs. Recorded under Nomarski DIC with a horizolntal field of view of approximately 400 microns.