<Ul> <Li> Austrolithoideae </Li> <Li> Choreonematoideae </Li> <Li> Melobesioideae </Li> </Ul> <Li> See also the ancestral Solenoporaceae </Li> <P> Coralline algae are red algae in the order Corallinales . They are characterized by a thallus that is hard because of calcareous deposits contained within the cell walls . The colors of these algae are most typically pink, or some other shade of red, but other species can be purple, yellow, blue, white or gray - green . Coralline algae play an important role in the ecology of coral reefs . Sea urchins, parrot fish, and limpets and chitons (both mollusks) feed on coralline algae . In the temperate Mediterranean sea, coralline algae are the main builders of a typical algal reef, the Coralligène ("coralligenous"). Many are typically encrusting and rock - like, found in marine waters all over the world . Only one species lives in freshwater . Unattached specimens (maerl, rhodoliths) may form relatively smooth compact balls to warty or fruticose thalli . </P> <P> A close look at almost any intertidal rocky shore or coral reef will reveal an abundance of pink to pinkish - grey patches, splashed as though by a mad painter over rock surfaces . These patches of pink "paint" are actually living algae: crustose coralline red algae . The red algae belong to the division Rhodophyta, within which the coralline algae form the order Corallinales . There are over 1600 described species of nongeniculate coralline algae . </P>

What is the name of the small red macroalgae that develop a hard crust