An owl's sharp beak and powerful talons allow it to kill its prey before swallowing it whole, unless it is too big. Owls usually regurgitate the parts of their prey that they cannot digest. These parts include bones, scales, and fur. Scientists who study the things that owls eat can get clues by studying the parts that the owl spit back out, called "owl pellets". These "owl pellets" are often sold by companies to schools for use in the students' biology and ecology lessons.