Ring "Ouroboros", or the snake (dragon), biting tail, is symbol of time and cycle life. It is a symbol of eternity in alchemy and comes from the magic of Ancient Egypt. This occult symbol is widely used in various schools of mysticism.
This symbol has many different meanings. The most common interpretation describes it as a symbol of eternity and infinity, in particular - the cyclic nature of life: the alternation of creation and destruction, life and death, constant rebirth and death.