Like plants, algae have cell walls contain either polysaccharides such as cellulose (a glucan) or a variety of glycoproteins or both. The inclusion of additional polysaccharide in algal cell walls is used as a feature for algal taxonomy. Mannas form microfibrils in the cell walls of a number of marine green algae including those from the genera Codium, Acetabularia as well as in the walls of some red algae like Porphyra.