POSTED: October 23, 2021
A quick note to self, occasioned by the fact that I read a word in a review of a comic book that I had to go away and look up. When a dragon or a serpent eats its own tail it forms a symbol usually known as an Ouroboros.
This symbol has a long history that starts in China, passes through Ancient Egypt, and goes onto to include gnosticism and alchemy.
Wikipedia might prove a useful starting point, if you want to know more.