This pendant is a slice of the quaternion Julia set. Quaternions are a sort of supercomplex number with four separate components, so the Julia set in quaternion space is a four-dimensional fractal, of which we can only ever see three-dimensional 'slices'. There are many variations on the quaternion Julia set and many ways to slice it (and you can find more examples in our shop and elsewhere here on Shapeways).
This pendant forms a set with our Julia's Basket earrings.