The “Naked” Singularity
Another possible ultracompact object that is allowed by General Relativity is a singularity that lacks both extension and a black hole horizon. It is often called a “naked singularity”.
Often I have wondered if the electron might be a horizonless singularity. As far as we know it its radius is indistinguishable from that of a point source, and it certainly is one of the most fundamental objects in nature.
Interestingly, no one has ever convincingly retrodicted the mass of the electron. This is just another mystery in a very long list enigmas (like the fine structure constant and the vacuum energy density crisis) that we don’t talk about much because we don’t have facile answers for them.