Coralline algae are calcifying red algae, which have a hard skeleton resulting from the precipitation of calcium carbonate within their cell walls. Coralline algae are abundant and widespread in coastal areas throughout the world, from polar regions to the tropics. They grow from the surface to depths of more than 100 meters; some under intense illumination, others with very dim lighting.
Coralline algae belong to the family Corallinaceae and are divided into two general types based on their morphology: geniculate corallines and non-geniculate corallines. The geniculate or articulated corallines are branched and flexible due to the presence of flexible uncalcified joints called genicula, between calcified segments. They grow as individual plants on rocks or granular substrates, but can also grow as epiphytes on shells or other algae. They primarily occupy intertidal and subtidal coastal areas.
The non-geniculate or