These algae are commonly found in freshwater environments, either free-floating or attached to surfaces in water and occasionally in soils. They are widely distributed across the globe. Individual cells of Monoraphidium range in size from 2 to 182 micrometers in length and 1 to 8 micrometers in width. The cell shapes vary from straight to lunate, sigmoid, or helical. Each cell contains a single nucleus, a parietal chloroplast, and typically a single pyrenoid, which may lack a starch sheath or be absent altogether. Asexual reproduction occurs through the formation of autospores.