  We investigated the magnon-photon coupling in an open cavity magnonic system,
which leads to two different nonreciprocal singularities dominated by the
dissipative coupling. One type of singularity is the exceptional point, which
is just on the exceptional surface in parameter space. The other type of
singularity is the bound state in the continuum discovered in the
level-attraction-like coupling, which is above the exceptional surface. In
experiment, we realized the two different singularities with nonreciprocity and
selectivity in an open cavity magnonic system with suitable dissipation rating.
Our results can be understood well with the pseudo-Hermitian theory of
magnon-polariton system.
