NURBs or Non Uniform Rational B-splines are a type of aproximating spline. This means that if you have 4 control points positioned like the coners of a square, the resulting spline would be a circle. NURBs allow you to creat complex surfaces with only a few UV coordinates. I made the model below using NURBs It's near impossible to produce such effects with a polygon modeler. Modeling with NURBs is alot like modeling with clay. Its 100x faster and easier. Im not sure the same applies for NURBs in Amapi tho.