An atoll is a low, ring-shaped island, or a series of arc-shaped islands, forming the rim of a shallow lagoon. The structure results from an accumulation of coral on top of a sunken volcano.
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- Formation of Bermuda reefs
- Darwin's Volcano – a short video discussing Darwin and Agassiz' coral reef formation debate
|This article is part of Project Glossary, a All Birds project that aims to write comprehensive articles on each term related to animals.|