Final answer:
The latest stage in coral reef development is an Atoll, which is a ring-like coral island surrounding a lagoon and represents the final stage after the original landmass has sunk below the water.
Step-by-step explanation:
The latest stage in coral reef development is an Atoll. Coral reefs undergo a series of developmental stages, the first being the fringing reef which is directly adjacent to land. This can develop into a barrier reef as it grows and separates from shore. Ultimately, if the landmass sinks below water due to geological activity, an atoll forms. An atoll is a ring-like coral island or string of small islands surrounding a lagoon, which is the remnants of a submerged volcano. Patch reefs, on the other hand, are isolated platforms within the lagoon of an atoll or barrier reef, and they do not represent a progression in the development of coral reefs.