Final answer:
The human "tailbone", also known as the coccyx, is a remnant of the tail that other vertebrate animals have. It serves as a support structure and aids in balance during sitting.
Step-by-step explanation:
The human "tailbone" is known as the coccyx, and it is considered a vestigial structure, meaning it is a remnant of a structure that had a function in the evolutionary ancestors of humans. The coccyx is composed of fused vertebrae at the base of the spine.
In other vertebrate animals, especially those with tails, the tail serves various functions such as balance, communication, and locomotion. In humans, the coccyx has lost its original tail-like functions, but it remains as a small, non-functional structure.
While the coccyx may not have a significant purpose in humans today, its presence reflects the evolutionary history of vertebrates, including our distant ancestors who had tails.