Closterium kuetzingii is a green algae species characterized by its crescent-shaped, long, and narrow cells. The cell wall is smooth and rigid, housing two large, lobed chloroplasts with pyrenoids in each cell half. The nucleus is centrally located in the isthmus, the narrow region connecting the two semi-cells. Reproduction occurs through cell division, forming a new semi-cell between the existing ones. The cell tips are slightly tapered or rounded, sometimes featuring terminal pores. Closterium kuetzingii exhibits slow, gliding movements facilitated by mucilage secretion.