Answer – A ring-shaped coral reef is called an atoll.
Explanation:
An atoll can be a ring- or oval-shaped coral reef, island, or series of islets surrounding a lagoon (a waterbody naturally separated from larger water bodies). Atolls are found in tropical and subtropical areas of the Pacific, Atlantic, and Indian Oceans. They are formed over millions of years by the growth and accumulation of coral and other marine organisms.
Initially, a volcanic island emerges through underwater volcanic activity. Coral colonies then establish themselves along the outer edges of the island, creating a growing coral reef. Over time, they build upward, extending the reef structure. Progressively, as the island subsides, the corals grow toward the water’s surface. Eventually, the central portion of the island sinks below sea level, creating a lagoon within the circular coral reef.
