Our ocean's corals reefs have been created when hundreds of hard or stony coral colonies construct a place to live.
Within the scientific class Anthozoa are these reef-building hard, stony corals in the order Scleractinia. These corals occur in all the world’s oceans and have established the spectacular ecosystems of today’s modern coral reefs. Although some of the 1000 stony coral species are solitary, most are colonial and reproduce to form multi-polyp colonies that share a common reef-building skeleton.
Aquarists further categorize stony coral colonies based on the size and appearance of their polyps. This categorization is especially helpful as coral aquarium care varies by grouping. Small Polyped Stony (SPS) corals have small polyps and are typically branched or plate-shaped. SPS corals require higher levels of care than other types of coral; reef aquarists pursue the keeping of SPS corals as their expertise grows due to the beauty and variety of coral collection that can be achieved.