Encountering a sunfish, or mola mola, was one of the most surreal diving experiences I’ve ever had. These fascinating creatures develop their truncated, bullet-like shape because the back fin they are born with never grows. Instead, it folds into itself as the enormous creature matures, creating a rounded rudder called a clavus. The name "mola" means "millstone" in Latin, describing the ocean sunfish’s somewhat circular shape.