Hard coral, also known as stony coral, is a type of marine organism that forms the backbone of coral reefs. These corals have a rigid skeleton made of calcium carbonate, which provides structure and support. They play a crucial role in creating habitats for various marine species, contributing to biodiversity in ocean ecosystems. Hard corals grow slowly, often taking years to form large structures. They reproduce both sexually and asexually, allowing them to spread and thrive in suitable environments. Healthy hard coral populations are vital for maintaining the balance of marine ecosystems and protecting coastlines from erosion.