In my novel, The Ouroboros Key, the symbol is the Ring of Unity created by Tiamet and Enki to aid in bringing unity to the world of humanity.
Wikipedia will tell you that the Ouroboros originated in Ancient Egypt and represented cyclic recreation.
It is also known as the Ring of Unity, which we first hear about in Ancient Sumeria (read Realm of the Ringlords: beyond the portal of the twilight world by Laurence Gardner).
The ring is depicted as a snake or serpent holding its tail in its mouth.
This same “ring” (according to the late Laurence Gardner) is the basis of most ring-lore in legend and history including references in The Lord of the Rings books by LRR Tolkien and The Ring Cycle by Richard Wagner.