Crustose coralline algae
Lithothamnion spp.
Description:
This genus contains a dozen of species in the Caribean. They are all heavily calcified and some have lost all superficial resemblance to algae. They vary from encrusting forms coating over dead coral to forms that both encrust and grow upwards as stony, branching plants. Occasionally their outer edges extend outward from the substrate. They vary in color from white through pink to vinous purple.
Habitat:
They are commonly seen on coral reefs, where they play an important role in cementing coral fragments.
Distribution:
Common Florida, Bahamas and Caribbean.
Remarks:
The different species are difficult to identify, except by sectioning and microscopic examination.