How do red algae differ from brown and green algae?

Red algae or crimson algae are the deepest algae that can be found at depths from 150 meters to 200 meters. Unlike green and brown algae, the accumulating substance in them is purple starch (while in green algae it is just starch, and in brown algae it is kelp). Their color, that is, red, is due to the presence of the pigment “phycoerythrin”, as this type of algae has one of the most difficult methods of reproduction and they mainly live in aquatic ecosystems.