Talk about red algae

Marine organisms, live in fresh water or attached to rocks, Thallus is rarely unicellular, filamentous or parenchymatous. Reserve is floridean starch granules. Pecto-cellulosic cell wall consists of outer mucilaginous layer agar and carrageenan (jelly) which prevents colonization by other organisms reducing light exposure. Some incorporate calcium carbonate in cell wall participating in building coral reef, few devoid of assimilating pigments are parasitic.