Brain corals get their name from their maze-like grooved surface. This pattern is a hard skeleton made of calcium carbonate extracted from the ocean by the polyps which live in the parallel grooves of the coral surface. The mega-grooves protect the polyps and their tiny tentacles, while the micro-ridges are home to algae. The polyps and algae have a mutualistic relationship where they provide food for one another in the form of photosynthesis and waste recycling.