forms unbranched filaments which are attached on stones or plants. The cell type which is able to divide more than one time get rib-likebands which go all round the cell when they divide. So the number of ribs indicate the number of divisions the cell has undergone. Scale bar indicates 25µm.
Sample from a little creek near Kiel. This image was taken using Zeiss Universal with Olympus C7070 CCD camera.