The Red Sea is an underwater paradise mainly because of one thing: the Coral Reefs.

Coral Reefs form via colonies of a stationary animal with a calcified skeleton. The coral animals feed by filtering plankton from the water, driven its way by sea currents. As the animals die off, their skeletons form the basis of the reef, and other animals adhere to the mass, and the cycle continues.

Corals also have algae living within its tissue. These algaes use photosynthesis to build up nutrients from sea minerals and dissolved carbon dioxide. It is the algae that give the corals their varying colors.

	This is called a "brain coral", because it looks somewhat like a brain. It can grow to immense proportions.
	Some corals are made out of spikes or horns, and grow in fan shaped colonies.
	Others also fan out, but are more flat, with no spikes.
	Colors can vary, and almost span the entire spectrum. I do not recall any green colored ones, but saw everything from cyan, violet, yellow, orange, red, ...etc.
	The dead corals form the substrate for the new corals to grow on. Dead corals are white or grey, and if algae start to grow on it can be blackish as well. A healthy reef has lots of colors.
	Many shapes of corals in this picture.
	As the water deepens, the yellows, orange and red parts of the spectrum get absorbed by the water, and only the blues remain, fading into greys.