Corals are the largest living structures on our planet, made up of thousands of tiny animals called polyps. Its these colonies of coral polyps that make up the large coral ‘heads’ that we are so familiar with in marine aquaria. Each polyp is only a few millimeters in diameter and all the polyps on the coral head are genetically identical. Polyps lay down a calcium-rich exoskeleton from calcium that they obtain from seawater. While the rate of formation of this hard skeleton varies with the species of coral, the process is light dependent, and night time rates are about 10% of the rate during daytime peaks.
Visit the Museum and see recent coral as well as fossil coral heads dating from the Mississippian period about 350 mya to Favosites, an extinct fossil genus from the Ordovician to the Permian period (488 to 251 mya).