The colors of these algae are most typically pink, or some other shade of red, but some species can be purple, yellow, blue, white, or gray-green.

In the temperate Mediterranean Sea, coralline algae are the main builders of a typical algal reef, the Coralligène ("coralligenous").

[6] Unattached specimens (maerl, rhodoliths) may form relatively smooth compact balls to warty or fruticose thalli.

A close look at almost any intertidal rocky shore or coral reef will reveal an abundance of pink to pinkish-grey patches, distributed throughout the rock surfaces.

[17] Some corallines slough off a surface layer of epithallial cells, which in a few cases may be an antifouling mechanism which serves the same function as enhancing herbivore recruitment.

The common Indo-Pacific corallines, Neogoniolithon fosliei and Sporolithon ptychoides, slough epithallial cells in continuous sheets which often lie on the surface of the plants.

Epithallial shedding in most corallines is probably simply a means of getting rid of damaged cells whose metabolic function has become impaired.

The corallines have an excellent fossil record from the Early Cretaceous onwards, consistent with molecular clocks that show the divergence of the modern taxa beginning in this period.

[1] This said, non-mineralizing coralline algae are known from the Silurian of Gotland[19] showing that the lineage has a much longer history than molecular clocks would indicate.

[21] Stem group corallines are reported from the Ediacaran Doushantuo formation;[20] later stem-group forms include Arenigiphyllum, Petrophyton, Graticula, and Archaeolithophyllum.

Crystal morphology within the calcified cell wall of coralline algae was found to have a high correspondence with molecular studies.

[24] According to AlgaeBase: According to the World Register of Marine Species: According to ITIS: Fresh surfaces are generally colonized by thin crusts, which are replaced by thicker or branched forms during succession over the course of one (in the tropics) to ten (in the Arctic) years.

[28] While coralline algae are present in most hard substrate marine communities in photic depths, they are more common in higher latitudes and in the Mediterranean.

[29] Their ability to calcify in low light conditions makes them the some of deepest photosynthetic multicellular organisms in the ocean,[30] having been found as deep as 268 metres (879 ft),[31] and as such a critical base of mesophotic ecological systems.

[37] In 1837, Rodolfo Amando Philippi recognized coralline algae were not animals, and he proposed the two generic names Lithophyllum and Lithothamnion as Lithothamnium.

Larval settlement is adaptive for the corallines because the herbivores remove epiphytes which might otherwise smother the crusts and preempt available light.

It also has significance at the community level; the presence of herbivores associated with corallines can generate patchiness in the survival of young stages of dominant seaweeds.

For example, off eastern Canada, Morton found juvenile sea urchins, chitons, and limpets suffer nearly 100% mortality due to fish predation unless they are protected by knobby and undercut coralline algae.

However, the most common species in the region, Hydrolithon onkodes, often forms an intimate relationship with the chiton Cryptoplax larvaeformis.

This combination of grazing and burrowing results in a peculiar growth form (called "castles") in H. onkodes, in which the coralline produces nearly vertical, irregularly curved lamellae.

They require high and persistent wave action to form, so develop best on windward reefs with little or no seasonal change in wind direction.

This is particularly significant in Britain and France, where more than 300,000 tonnes of Phymatolithon calcareum (Pallas, Adey & McKinnin) and Lithothamnion corallioides are dredged annually.