Hard corals are also known as stony corals and are categorized into two different types which define them by size, namely LPS (large polyp stony), and SPS (small polyp stony).
Hard corals grow in big colonies and bond together to form the large rocky structures that are visible when we go diving in the tropical seas.
As living creatures, they feed off the marine life around them with the SPS corals feeding off the algae plankton and LPS corals eating small fish and crustaceans.
Corals are living creatures, and 25% of all marine life needs corals to help support them.
They are made up of microscopic animals called coral polyps, and that plus their skeletons which are left behind after they die are what forms the solid coral structure.