Filled spherical shell region between two radii consumed by Volume/SurfaceArea/RegionCentroid
SphericalShell[c, {r inner, r outer}]
Volume[SphericalShell[{0, 0, 0}, {Subscript[r, inner], Subscript[r, outer]}]]
→ (4*Pi*(-Subscript[r, inner]^3 + Subscript[r, outer]^3))/3RegionCentroid[SphericalShell[{Subscript[c, 1], Subscript[c, 2], Subscript[c, 3]}, {Subscript[r, inner], Subscript[r, outer]}]]
→ {Subscript[c, 1], Subscript[c, 2], Subscript[c, 3]}Graphics3D[{Opacity[0.5], SphericalShell[]}, Axes -> True]
→ -Graphics3D-