Access curve from object

I might be blind today,
but is there any (documented) way to access a curve data block from an object data block ?

In this case I have the object (SurfSphere) and need the material,
but once I got the curve that should be easy…

getData() just like a mesh or anything else…

well, except nurbs surfaces I guess [I didn’t try lattices either]

That’s what I tried (before even looking at the documentation),
but that doesn’t work.

I guess I’ll have to look at the source … again.
Just to find that it isn’t implemented yet … again.