The Mobius strip, at its simplest, may be modeled by taking a flat strip of paper and giving it a half twist before joining the ends. The resulting structure has many intriguing properties, most notably the fact that it has only one surface and one edge. A variety of fascinating hollow structures may be generated from the notion of a non-orientable surface, and metal crochet offers a versatile construction method.
The properties of the mobius and its derived structures make it a natural symbol for the unity of all things and the illusory nature of duality. It has also been used to represent concepts such as rebirth, and the cycles of continuous change and renewal in the natural world.
My own Cocoon pendant in silver, gold, and amber:

I was intrigued by the idea of combining a symbol of One-ness with a form that is intrinsically sheltering and nurturing.
Further resources:
Mathematics of the Moebius strip and related structures such as the Cross-cap and the Klein bottle.
The Moebiustorus - a fabulous sculpture by Rinus Roelofs - the rest of the gallery is also well worth a look.
Battered Moonlight - a sculpture by George Hart.
M.C. Escher's famous Ants woodcut.