Just about everything I have read about antimatter talks about proton/antiproton, electron/antielectron, and neutron/antineutron annihilation. But what happens if, for example, a proton and an antineutron collide? Would a weird nucleus be created or would there be a partial annihilation with some leftover quarks and antiquarks? Other outcomes? It is easy to imagine a simple process where the antineutron in a short-lived nucleus undergoes beta decay and the resulting antiproton annihilates the proton ... but does that HAVE to happen?