What are phycocolloids ? List their functions

Brown algae have a colloidal covering over their cellulosic cell wall, consisting of a mixture of polysaccharides collectively called phycocolloids. e.g., alginic acid (algin), fucoidin and fucin. These prevents drying or freezing (in water), when algae are exposed to air during low tides and protect cells when waves beat them against the rocks.