Although the ouroboros may make its most famous appearance in ancient Egypt on the second shrine in the tomb of Tutankhamum, some of the more interesting and less well known examples are uterine amulets. Uterine amulets, as one might suspect, were a class of amulets used to influence the uterus, specifically conception and childbirth. Appearing at the edge of the amulets, the ouroboros serves to enclose the uterus, opening and closing as necessary, acting as a boundary to both what's inside and what's outside.

For the Norse, a great serpent of the sea known as Jörmungandr, a child of the great trickster god Loki, managed to grow so large that it circled the globe and then bit its own tail to close the circle. Their mythology predicts that not even Thor will survive an encounter with this world serpent since at the end of the rule of the gods, known as Ragnarök, they will simultaneously slay each other.

Although it is but a small geometric step from the two-dimensional representation of the coiled serpent to the circular serpent, the change in symbolic meaning is enormous. As a circle, it is elevated to a completely different class of symbols that are cyclic, symmetric, all encompassing, moving, and even eternal. For the alchemists, the ouroboros represented a contained, cyclical process such as the water cycle of heating, evaporation, cooling and condensation, which was used to purify liquids. But in their quest for fundamental knowledge and control of substances, it also represented unity born out of the joining of opposites. The snake eats itself and feeds itself simultaneously. It kills itself and rejuvenates itself, moving forward only to return to where it began.

Tattoo versions of the ouroboros are as varied as the symbols history. From a simple garden variety snake to the great feathered serpent Quetzalcoatl, ouroboros tattoos have the added advantage of being used as arm or leg bands, making their eternal circle in three dimensions instead of just two.