An ouroboros depicts a snake or (more rarely) a dragon devouring its own tail. It represents the eternal cycle of destruction and rebirth. 
 
Over 3,500 years ago, one of the earliest known ouroboros was placed in the Enigmatic Book of the Netherworld, an ancient Egyptian funerary text from the tomb of Tutankhamun, from 1400 BCE.
 
Associated with alchemy, this ancient symbol is considered an emblem of wholeness or infinity.