Our “tailbone” was called the “cuckoo” by the Greeks who thought it resembled the beak of the bird of the same name. This structure is a fusion of three or four vertebral bones, greatly reduced in size, that is attached to the end of our spinal column. In rare instances an individual is born with an extended tail, 4 to 6 inches long. The tail is removed surgically at or shortly after birth without functional consequences. In the middle ages the coccyx was also called the “wind whistle”. I will let you contemplate the possible origins or associations of such a name!