Closterium. Light micrograph (LM) of a desmid, Closterium. The desmids are a group of unicellular green algae characterised by their beautifully shaped cell walls. The cell is split into two halves, joined by a waist. Cell division is accomplished by splitting in two at the waist, with each half generating a perfect replica of itself to restore the original shape. Magnification: x280 when printed 10 centimetres wide.