What is the pattern of this case?

Ripple is a pattern that people call "wealth never stops". It is a geometric pattern, which comes from the thunder pattern on ancient pottery and bronze ware. Because it is a square or circular pattern composed of short lines, it is called palindrome.

In the history of China, there are four types of palindromes: square-back simple style, stick figure combination style, positive and negative ""style and one-stroke continuous writing style.

Some palindrome pictures: