Xuangui is a legendary creature from the ancient Chinese bestiaries. It was described as a black turtle that twisted their bodies as they swam. They dwelled in lakes and pools in the mountains of China. It is said that wearing one of these turtles as a belt would prevent oneself from becoming deaf.
The image above is an original pen and ink drawing from a later edition of the Chinese book Guideways Through Mountains and Seas. The original scripture was complied during the Warring States period and the Western Han dynasty (4th century - 1st century B.C.E.).