Coral reefs are colorful limestone communities where polyps can live. Polyps are very small and soft organsms with a strong skeleton called a calicle. A polyp will attach itself to a rock on the ocean floor and begin to divide itself into thousands of clones. All of the calicles will then connect together creating colonies that then combine to create a reef community that acts as one organism growing for thousands of years. The algae called  zooxanthellae lives on the polyps and gives them their diverse colors. Bleaching occurs when corals begin to get rid of (eliminate) the colorful algae due to stress from temperature and pollution. This stress will slowly kill the colony.

Corals live close to the surface since the feeding process begins with the sun.The algae uses sun rays for photosynthesis and produces byproducts that corals can live off. Corals also have tentacles that are most commonly used at night to grab small fish and zooplankton.

These reefs cover 1% of sea floors and support up to 25% of marine animals. Additionally, the oldest growing reef could have started 50 million years ago. However, this can all change now that scientists are predicting the dying of all coral reefs in as close as the next 30 years due the negative human impact with factors like water and air pollutions, and global warming.