Corals are a polyp species that belong to the class Anthozoa of phylum Cnidaria. These polyps are connected to each other through calcareous channels. After the polyps' death, another coral grows on the old calcareous skeleton, and thus coral reefs appear. The coral calcareous skeletons commonly appear in red and white. Due to its beauty, this skeleton is used by humans to make artifacts, jewelry pieces, and decorative objects. Corals represent the living environment for numerous ocean species (in fact, for ⅓ of the ocean species). Their growing quotas are extremely variable, depending on environmental conditions or on the species. There are many types of corals, ramified, flat, massive, brain, and those that look like paper or foil. Many of these can be kept in aquariums. You only need to keep in mind their specific needs and particularities. Coral Types and Characteristics Sinularia enjoys medium lighting, and does not require direct feeding. It spreads very easily. It grows very fast and can also feed very fast. As previously mentioned, medium lighting is better than small lighting. Sarcophyton latum requires medium luminosity/brightness. It is not an aggressive species and is easy to grow in an aquarium. Sarcophyton elegans has a unique look. It has a very difficult resistance and does not respond positively to stress conditions. It is sensitive to the human touch. Although it will not die if touched, it may get quite stressed out. It requires medium to high luminosity conditions, needing more light than Sarcophyton. Its placement varies depending on the aquarium's conditions. Sarcophyton is incredibly easy to spread. It is the perfect type of coral for those who are not familiar with keeping an aquarium. It can tolerate any type of luminosity, and is more sensitive to the water quality. It can be placed almost anywhere, even in darker rocks. It is an aggressive species, as it can spread out toxins in the aquarium that can harm other corals. Hydnophora has a medium resistance and requires high luminosity. Its placement depends on the light. It is easy to feed with any nutrients. This type has been spread in captivity. If you offer it a lot of light, it is easy to grow in an aquarium. Heliofungia is a beautiful coral with long and colorful tentacles. It can be also found in local fish shops. It is a very healthy species and can survive the first few months in captivity with a very good reaction to change. It requires a lot of light. Tubacrea, the sun coral, is indeed a magnificent species. It has unusual colors such as yellow, orange, and black. It does not contain algae that makes corals photosynthetic. As it is not photosynthetic and grows in darker places, it can survive longer. It can live happily in both types of environment, luminous or darker. It is placed on a substrate or on small rocks. It must be regularly fed with small, cut pieces of food, and each piece of polyp needs special, particular care. It can propagate due to its capacity to reproduce within its body and form the polyps. It is non-aggressive. It does imply a lot of difficulties to be grown in an aquarium. If during the feeding process, all polyps do not receive food, the unfed ones die. Miss Ricordia is a wonderful coral. It is beautifully colored, easy to take care of, and small enough to live in an aquarium. Also, it does not require a lot of light. It is very adaptable and likes any type of luminosity, from fluorescent light to strong light. The difference in lights affects its color and growth to a certain extent. It may sting and destroy its neighbors, so it should not be placed close to other coral species.