Reference:Finite Solid Primitives
There are seventeen different solid finite primitive shapes: blob, box, cone, cylinder, height field, isosurface, Julia fractal, lathe, ovus, parametric, prism, sphere, sphere_sweep, superellipsoid, surface of revolution, text and torus. These have a well-defined inside and can be used in CSG: see Constructive Solid Geometry. They are finite and respond to automatic bounding. You may specify an interior for these objects.