The coral is a small animal, a polyp, that has tiny tentacles for the
purpose of feeding from microscopic zooplankton. ~ac? polYp
secretes a calcareous skeleton that remains behind when It dies, ThIS
is how reefs of coral build up through time and eventually achieve a
thickness of hundreds of metres; growth rates are usually between 1
cm and 100 cm per year. Coral skeletons have a great variety of f~rms
such as spherical, cup-shaped, star-shaped fan-shape.d a~d pillarshaped.
The symbiotic relationship that corals have ",:th tmy algae,
known as zooxanthellae, contributes to the great vanety of colours
found in the living coral reefs.