  The superradiant instability of Kerr-AdS black holes is studied by
numerically solving the full 3+1 dimensional Einstein equations. We find that
the superradiant instability results in a two stage process with distinct
initial and secondary instabilities. At the end of the secondary instability
the geometry oscillates at several distinct fundamental frequencies -- a
multi-oscillating black hole. The multi-oscillating black hole is remarkably
close to a black resonator, albeit with a bit of gravitational hair. During the
hairy black resonator epoch, the evolution of the horizon area is consistent
with the exponential approach to a constant. By employing different seed
perturbations in the initial Kerr-AdS geometry, we also demonstrate that the
black resonator's hair is not unique. In the dual quantum field theory
description, rotation invariance is spontaneously broken and the energy density
is negative in some regions, signaling an exotic state of matter which does not
relax to a stationary configuration.
