Division rhodophyta
Organisms with widely varying morphology, from unicellular forms (quite rare) to more complex forms, called parenchymatous. They have chlorophyll a (green-coloured pigment) and pigments of other colours, such as phycoerythrin responsible for their red colour. As a storage product they contain a type of starch similar to the glycogen of animals. The cell walls are formed by colloidal substances (agars or carrageenans) which are used in various industries. So-called coralline algae present calcium carbonate in their cell walls, which if it is very abundant gives rise to algae with a consistency of stone. Within the red algae there are some freshwater species, but the majority are marine species and very abundant in tropical seas.
