Closterium nematodes is characterized by its elongated, slightly curved, thread-like cells. These cells are typically long and narrow, with smooth, unadorned walls. Each cell houses two deeply lobed axial chloroplasts with pyrenoids and a centrally located nucleus in the isthmus. The cell ends are rounded or slightly tapered, and during reproduction, a new semi-cell forms between the existing ones. Closterium nematodes exhibits slow, gliding movements likely facilitated by mucilage secretion.