Hard corals are generally broken down into two categories, large polyp stony (LPS) corals and small polyp stony (SPS) corals. The LPS corals are generally larger calcareous corals. They have much larger fleshy polyps than those of the SPS corals. LPS polyps are large and soft. Most of LPS produce long sweeper tentacles which they use to keep any other organisms a safe distance away. The degree of extension of the tentacles depends upon the amount of light, current, and whether the coral is feeding or not. Many LPS corals are quite hardy and are generally easier to keep in the aquarium than the SPS corals. For the most part they require less intense lighting and a lower water movement than SPS corals.