Also known as Brain coral or Pineapple coral. Diet: Photosynthesis and zooplankton Fun Fact: Polyps only extend and feed during the night. Each one has a small number of tapering tentacles which often have a darker colored tip (stinger tentacles, or sweeper tentacles). They use these to sweep the water to see if any other coral is in its area; if so, then they begin to sting the other coral. This is commonly known as coral war. Each coral is trying to make sure it has enough room around it so they can continue to grow and have more surface area for their offspring.