organisms that create a thin veneer of calcium carbonate over other surfaces. They need light to grow and create a cementing material between corals.
Coralline algaes are calcified (containing hard calcium-based structures) red algae that are typically divided into two groups: articulated and encrusting. Articulated corallines are branching and tree-like, and are attached to the substrate by root-like holdfasts. The encrusting corallines form crusts over the substrate and contain a substance that induces settlement of larval abalone.
Desireable encrusting calcium containing algaes. Various forms and colors (red, pink, & purple) are represented, as are both high & low light loving species. Adequate calcium & strontium are required for successful survival and growth. Usually accepted as an indicator of general tank "health".