A model for the vibrations of a cage molecule in terms of the motions of an infinitely thin spherical shell is applied to icosahedral C60. When appropriate values are given to the two free parameters, the model accounts for the general pattern, energy ordering, radial, and tangential characteristics of the vibrations, giving results comparable to those from a six-parameter conventional valence force field. In the model, the lowest frequency of any spherical-shell molecule is the "d" squashing deformation that describes tidal waves on a flooded planet.