Desmodesmus denticulatus forms colonies composed of two, four, eight, or 16 cells aligned in a row, with ellipsoidal to ovoid shapes. The cells are connected to each other along their longer sides. Terminal cells of the colony, and sometimes medial cells as well, typically feature spines. The cell walls may exhibit ridges, warts, and a net-like structure. While this species typically produce colonies with multiple cells, they can also exist as single-celled organisms (unicells). These unicells may resemble Lagerheimia, another genus of single-celled algae. The cell wall of this species consists of an outer layer with a net-like structure and underlying “rosettes” of tubes. These details are not observable under standard light microscopy but become visible under higher-resolution techniques like scanning electron microscopy (SEM) or transmission electron microscopy.