How to describe the pattern on the tortoise?

The pattern of the turtle's back and abdomen is basically fixed, and the three pieces in the middle of the carapace represent the talents of heaven, earth and man respectively. The outer three colors are 10 yuan, representing working days 10, and the outer circle is 24 yuan, representing 24 solar terms. Abdominal stria 12 stands for 12 ground branch.

There are different pieces of tortoise shell in different species, but even the tortoise shell is 13 pieces. Of course, the edge may be different, depending on whether there is a neck shield, that is, a small piece at the back of the neck, which some turtles do not have.