Corals get their color from the algae living within them and most Bermudian coral are yellow or green, with some purples that stand out. Bermuda's famous pink beaches are produced by eroded foraminiferan shells called tests. Foraminiferans are one celled animals whose thread-like pesudopodia extend through holes in its test.
Corals seem so inanimate.
There is serious competition in the coral reef. Two ways corals compete for space are, overgrowing or directly attacking neighbors who might receive a sting. When sunlight composed of the spectrum of colors strikes water, blue is the color scattered most by the water molecules. Thus more blue is reflected back to the surface. The brilliant blue of Bermuda's oceans is due to the purity of the waters - they contain little organic matter and few organic waste products.