  We predict a universal mid-gap bound state in topological superfluids,
induced by either non-magnetic or magnetic impurities in the strong scattering
limit. This universal state is similar to the lowest-energy Caroli-de
Gennes-Martricon bound state in a vortex core, but is bound to localized
impurities. We argue that the observation of such a universal bound state can
be a clear signature for identifying topological superfluids. We theoretically
examine our argument for a spin-orbit coupled ultracold atomic Fermi gas
trapped in a two-dimensional harmonic potential, by performing extensive
self-consistent calculations within the mean-field Bogoliubov-de Gennes theory.
A realistic scenario for observing universal bound state in ultracold $^{40}$K
atoms is proposed.

Quantum Gases;Mesoscale and Nanoscale Physics;Strongly Correlated Electrons;Superconductivity