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  1. Coral Reefs - National Geographic Society

  2. Coral reef - Wikipedia

  3. Coral reef | Description, Geochemistry, Origins, & Threats

  4. Coral reef ecosystems - National Oceanic and Atmospheric Administration

  5. Coral - National Geographic Society

  6. Reef - National Geographic Society

  7. Coral Reefs 101 | National Geographic - YouTube

  8. Coral Reefs Ecology & Biodiversity - Coral Reef Alliance

  9. Coral Reefs - NOAA's National Ocean Service

  10. Scientists are trying to save coral reefs. Here's what's working.