  Light-ring bifurcations that can occur for prolate non-Kerr compact objects
can leave an indelible signature on SMBH shadows as a fractal sequence of
eyebrow-like formations. These fractal features are the result of two
properties of these spacetimes. The first is that they allow for multiple
escapes for the photons (throats in the effective potential of photon geodesic
motion). The second is that photon geodesics can resonate between different
generalized light-rings related to the escapes, called fundamental photon
orbits, that lead photons to alternate between the different exits either
towards the compact object or infinity. The resulting fractal structures of the
shadow seem to be a generic feature of prolate non-Kerr objects that may be
observable in (accretion-disk)-illuminated compact objects, especially along
equatorial lines of sight, but the best orientation depends on the specific
parameters. Such fractal features if observed in the shadows of singular
supermassive black holes at the centers of galaxies, would be smoking gun
signals of non-Kerr compact objects.
