Stony coral are the hermatypic (reef building coral) that belong to the taxonomic order Scleractinia. They are marine animals that are more specifically called stony star corals. Other stony coral include the fire coral, organ pipe coral, etc.
Scleractinia's along with every other ocean creature, were created on the fifth day of creation. They dated by uniformitarian geologists to have lived as far back as the Middle Triassic. It is determined that they are closely related physically to sea anemones. The only thing that separates it from the sea anemone is its hard outer skeleton. It is therefore believed to share an ancestral relationship with the the extinct tabulate or rugose corals. Its pattern of septa is six-rayed leaving it to be called a hexacoral. They are divided into 2 main groups. The first group is the reef builders. They are mostly found in clear shallow waters where they can get lots of sunlight and nutrition. The second is a group of coral that prefers the dark and living off of any organisms that comes down to its territory. You will read more about this in the anatomy section.
A scleractinia can be classified as either two things. Solitary or compound. The horn-shaped scleractinia is the most common coral known. In that coral it reproduces asexually causing to make colonies. Sometimes even those colonies fuse and create more colonies. The skeleton for the scleractinias are composed of calcium carbonate. It is a thin basal plate that the septa vertically arise. Each individual polyp skeleton in the coral is known as a corallite. Septas are created by mesentries and are considered as so. Even though there are many different kinds and ages of septas each are closely related by one another. Each either have radial or bilateral symmetry. Each septa is aligned on the coral according to age. Both solitary and compound scleractinias are light and porous as compared to the rugosa which is solid.
In the scleractinia family there are two main structures. The first is Stereome. Stereome is a layer of secondary tissues which cover the surface. It is made of bundles of aragonitic needles that protect the scleractinia. The second is Coenosteum which is a complex tissue that seperates each individual corallites.
Along with classifying them as solitary and compound or stereome and coenosteum. There is also one more way to to classify this coral even more. And here are the four ways:
- Pachytecal- very thick walled and undeveloped septas
- Thick Trabecular- septas built with thick structures looking like beams which are called trabecules
- Minitrabecular-septa with thin trabecules
- Fascilcular or non trabecular- coral built with no septa made my trabecules, but from aragonite fibres. 
There are two types of reproduction. The first is intratentacular reproduction. During intartentacular reproduction polyps are separated and spread across the stomodaeum where each bud takes a part of the stomodaeum and from there regenerates its self. The other type of reproduction is the exintartentatcular reproduction. Exintartentacular is taken place outside of the parents body and they leave with no part of the parents stomodaem as compared to the intratentacular reproduction.
Sleractinia falls into two major categories. The first is the zooxanthellate. In these corals, they are filled with symbiotic algae in the endodermal cell. The symbiote is really beneficial to the coral because it makes nearly 95% of the corals food. Oxygen is also brought into the coral by photosynthesis, which allows the plant to grow as much as three times faster then it would alone. These corals grow at a range from 200 feet(60 m) below surface. It does so because it has warm water, lots of sunshine, a good amount of oxygen, and a sturdy non muddy surface to plant its roots on and settle.
The other type of category is the non-zooanthellate. This type of coral is not a reef baring coral. It is often found up to 6000 meters below water. They desire to live in dark cold places, where they get their energy from eating off plankton and other organic articles floating around. The structure of this coral is more capable of being affected by others and contains less calcium carbonate then the zooxanthellate. The reproduction of these corals are a lot less as compared to those of the zooxanthellate.