  We propose mechanical systems, described by Newton's equation of motion, as
suited platforms for symmetry protection of non-Hermitian topological
degeneracies. We point out that systems possess emergent symmetry, which is a
unique properties of mechanical systems. Because of the emergent symmetry, in
contrast to other systems, fine-tuning of parameters (e.g., gain and loss) is
not required to preserve the symmetry protecting exceptional rings in two
dimensions. The presence of symmetry-protected exceptional rings (SPERs) in two
dimensions is numerically demonstrated for a mechanical graphene with friction.
Furthermore, classification of symmetry-protected non-Hermitian degeneracies is
addressed by taking into account the above special characteristics of
mechanical systems.
