You know, you're right, I do remember that being about stars now. Thanks for the little lesson, my astrophysics course never got quite that deep :)

They're represented as a singularity, and for all all intents and purposes it's a good approximation because the event horizon is always larger than the radius, but they do have a diameter. They form when the opposing forces between adjacent electrons and protons is overcome by the gravitational force, but the subatomic particles didn't go anywhere, they're just stacked on top of each other rreeeaaallll tight