Corals likely enjoy a few perks from living near each other. Being tucked within a cluster may provide shelter from predators. And the more corals occupy a patch of land, the better they can break up oncoming waves. This means each coral is less likely to be dislodged during a storm. A cluster can also disrupt seawater as it flows over the reef so it swirls around and better distributes nutrients among the colony. More neighbors means more potential mates, too. “You want to be close together so you give your babies the best chance of being fertilized,” Edwards says.