Owls are expert night hunters of birds, lizards, insects, mice, or even fish. Various adaptations make them skillful at catching prey in low light. The feathers across the front of their faces are flattened into a disk, surrounded by a fluffy ruff, which channels sound toward the ears. In many owls, uneven placement of the ears on their skull allows them to pinpoint the location of sounds with extreme accuracy. Owl eyes have extra light-sensing cells (rods) packing into tubular eyeballs that extend back into their heads. The eyeballs cannot move in their sockets, but owls instead swivel their necks more than 180 degrees to see what is behind them. Fringed, soft feathers on their wingtips act as mufflers, making for silent flight as owls sneak up on prey. Owls regurgitate parts of their meals, spitting out a pellet made of fur, feathers, bones, or other indigestible body parts.