Septum (coral)
From Infogalactic: the planetary knowledge core
In corals, a septum (plural septa) is one of the radiating vertical plates lying within the corallite wall. Outside the corallite wall these plates are known as costae (singular costa).[1] The septa may be thick, thin or vary in size. They may have teeth which range from needle-like to blade-like and are often characteristic of different genera.[2]
