What purpose do turtle shells serve in traditional healing practices?

Turtle shells are often used in traditional healing practices as a means to stimulate weak kidneys and help in the removal of gallstones. This is rooted in various cultural beliefs about the medicinal properties of turtle shells. In some cultures, they are thought to have qualities that promote bodily functions such as detoxification and support of the urinary tract, which in turn aids kidney health. There is a belief that the minerals and other elements found in turtle shells can provide therapeutic benefits that align with these healing functions.

The other options, while they may relate to different forms of traditional or alternative practices, do not specifically connect to the traditional use of turtle shells. Enhancing vision, relieving anxiety, or improving sleep quality are not commonly attributed to turtle shells in the context of traditional medicines, thereby making this answer the most appropriate in the context of the question.