Chinese civilization originated from the Yellow Emperor (Xuanyuan), and Gui Ling is the totem of Xuanyuan. In the pre-Qin period and before, the status of turtle was much higher than that of dragon, so it can be said that turtle is a symbol of the throne and state power. So turtles are widely used in tombs, especially in the early Han Dynasty. Stone turtles and bronze turtles were basically used to support coffin beds, and turtle monuments began to appear during this period. At that time, the tortoise carrying the monument was also called "turtle", and its overload came from the legend of the giant turtle carrying mountains at sea in Shan Hai Jing.
The stone tablet on the back of the tortoise looks like a tortoise, but it is actually a kind of god beast. If you look closely, it is not exactly the same as the tortoise. There are several legends about this god beast, but it is a legend after all. Personally, I think it is enough to know about it.
The most talked about is that the old turtle is one of the sons of the dragon, with the greatest strength and inexhaustible power forever. Legend has it that it helped Dayu control water. Seeing his boundless strength, Dayu was afraid of making trouble, so in order to restrain him to a certain extent, he set up a huge stone tablet engraved with his achievements on the grounds of reward. The stone tablet is heavy, so the movement is limited. After a long time, you can't move any more. It inspires people, it is powerful, carrying a stone tablet and never falling down, and its name will be passed down through the ages. Because it looks like a turtle, people later put a stone tablet (engraved with scriptures or historical achievements) containing the turtle in a certain position in temples or other buildings, which means eternal survival and inheritance. In this way, after historical inheritance, the tortoise shell monument has become a landscape in many ancient buildings and has been preserved to this day.
There are several legends about tortoise-back stele, and the above is the most popular one. After all, legends can't be verified. It's good to know a little.