Although coralline algae are notoriously slow growing plants, the fact that they are extremely abundant, often grow in dense stands, and are widespread in warm and cold waters, makes it important to consider their production. It is also prudent to emphasize that there are two major kinds of products, namely, organic and inorganic material. Organic productivity in coralline algae is lower than it is in many other marine plants and in hermatypic corals. Productivity responds in different ways to light intensity, with the prominent tropical ridge former Porolithon onkodes responding positively to high light intensity, in contrast to most other coralline species which are shade adapted. Inorganic productivity is high for populations of coralline algae, comparing favorably with that for calcifying animals. Marl and rhodoliths are unattached growths of coralline algae that may accumulate in large amounts. These structures contribute considerably to ocean floor sediments in both cold and warm parts of the world.