Corals are broke down into several categories hard and soft corals and long and small polyped corals. From beginner low light corals like mushrooms to more advanced Coral like a Torch Coral careful consideration should be given when adding any corals. All corals need different amounts of light to survive in an aquarium setting along with water flow and placement to not harm other corals inside an existing reef system. To help the environment look for propagated corals they can be easier to acclimate and less expensive.