Final answer:
Long bones have an epiphyseal plate that reveals age when present, but turns into an epiphyseal line as growth stops.
Step-by-step explanation:
Long bones in the body have features that can help determine a person's age. One such feature is the presence of an epiphyseal plate, also known as the growth plate. This is a layer of cartilage found at the ends of long bones, where growth occurs. The presence of an epiphyseal plate indicates that the bone is still growing. However, once growth is complete, the cartilage is replaced by bone and the epiphyseal plate becomes an epiphyseal line. Therefore, the absence of an epiphyseal plate and the presence of an epiphyseal line on a long bone can indicate that the bone has stopped growing, providing a clue to the person's age.