There are many designs and symbols said to represent eternity. The Endless Knot, the Ouroboros and infinity symbols all feature moving lines or curves that weave and connect with no discernible beginning or end.
The Endless Knot has roots in Tibetan Buddhist culture. It features interwoven lines and a series of right angles, representing the endless compassion and wisdom of the Buddha, as well as continuity. The Ouroboros is an ancient Egyptian symbol that depicts a snake or a dragon in a circle, eating its own tail. It represents the cyclical nature of existence, and was later adopted by the ancient Greeks. The infinity symbol, most often resembling the number "8" turned 90 degrees on its side, represents anything limitless.