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| | ipedia.com: Reef Article (Site not responding. Last check: 2007-10-14) |
 | | In nautical parlance, a reef is a rock, sandbar, or other feature beneath the surface of the water, but shallow enough to be a hazard to ships; see also shoal. |
 | | Many reefs result from abiotic processes—deposition of sands, wave erosion planning down rock outcrops—but the best-known reefs are those of tropical waters developed through biotic processes dominated by corals and calcareous algae. |
 | | There are a number of biotic reef types, including oyster reefs, but the most massive and widely distributed are coral reefs, limited to tropical waters. |
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