How do Sphere/Capsule Collision Shapes work

I just wondered how PhysX handles these kinds of shapes. Does it create a polygon shape for these shapes or does it treat them like mathematical shapes? And would it theoreticaly be possible to use NURBS surfaces as collision shapes without converting them to polygons?
Sorry for the not nxOgre related question.

They'd be treated as mathematical shapes; Spheres are a simple radius check and I assume capsules would be something similar.

Probably not, you may be able to mimic it with the particle system; fluids, cloth, soft bodies and adjust the particle size. But I'd doubt it.

Thanks for the fast answer.