https://en.m.wikipedia.org/wiki/Neutron_star#Structure
I think you're misremembering, we don't know what's at the center of a neutron star, or that there aren't other, more dense, types of stars.
I think you're misremembering, we don't know what's at the center of a neutron star, or that there aren't other, more dense, types of stars.
That’s what I get for treating modern physics as a kind of a vaudeville show ;)