In general, the Hypnea musciformis and the Hypnea cornuta are similar. Although the two are occasionally found together, the H. cornuta branches live in more arid environments. Its branches are thinner than those of H. musciformis, and each hook-like branch bears two or three horned starry hairs. The alga can reach a maximum length of 20 cm. The diameter of the branches is one millimeter. The hues range from an almost colorless olive-green to a brown or light tan.