It's such an amazing relationship. The Pistol Shrimp, a digger, has poor eyesight. The Goby, which lives in tunnels has good eyesight. The Goby will occupy the tunnel of the Pistol Shrimp, and in return, escorts the Pistol Shrimp to find food. They'll go out to forage like a team, the Pistol Shrimp always keeping one antennae on it at all times. If the Pistol Shrimp gets seperated from the Goby, the Goby will actually go get it, and escort it back to the tunnel. To summarize, the Goby gets a free home, and escorts the Pistol Shrimp out of the burrow to eat. If danger arrives, the Pistol Shrimp will be notified by the Goby and they both bolt to the burrow.