  The spacetime solution for a black hole, surrounded by an exotic matter
field, in Rastall gravity, is calculated in an arbitrary d-dimensional
spacetime. After this, we calculate the scalar quasinormal modes of such
solution, and study the shift on the modes caused by the modification of the
theory of gravity, i.e., by the introduction of a new term due to Rastall. We
conclude that the shift strongly depends on the kind of exotic field one is
studying, but for a low density matter that supposedly pervades the universe,
it is unlikely that Rastall gravity will cause any instability on the probe
field.
