What is carved on the shell of a hexapod turtle?

Liu Yi's tortoise shell is carved with symbols and patterns related to divination, not words. These symbols and patterns engraved on the tortoise shell can represent the six hexagrams, which are used to show the changes of the six hexagrams. The fortune teller will interpret the divination images according to the changes of yin and yang and make corresponding predictions. In modern practice, due to ethical and legal restrictions on the use of materials such as ox bones and tortoise shells, actual lettering is rarely seen. Therefore, Liu Yi's tortoise shell is engraved with symbols and patterns related to divination. This answer is for reference only. Don't be blindly superstitious.