  The angular dynamics of a very small ellipsoidal particle in a viscous flow
decouples from its translational dynamics, and the particle angular velocity is
given by Jeffery's theory. It is known that cuboid particles share these
properties. In the literature a special case is most frequently discussed,
namely that of axisymmetric particles with a continuous rotation symmetry. Here
we compute the angular dynamics of crystals that possess a discrete rotation
symmetry and certain mirror symmetries, but that do not have a continuous
rotation symmetry. We give examples of such particles that nevertheless obey
Jeffery's theory. But there are other examples where the angular dynamics is
determined by a more general equation of motion.
