  We discuss an algebraic treatment of four-body clusters which includes both
continuous and discrete symmetries. In particular, tetrahedral configurations
with T(d) symmetry are analyzed with respect to the energy spectrum, transition
form factors and B(EL) values. It is concluded that the low-lying spectrum of
16O can be described by four alpha-particles at the vertices of a regular
tetrahedron, not as a rigid structure but rather a more floppy structure with
relatively large rotation-vibration interactions and Coriolis forces.
