So, you know how everything is made up of little tiny things called atoms? Well, atoms are made up of even tinier things called protons, neutrons, and electrons.
But scientists think that there might be even smaller things that make up protons and neutrons. And they call these things "preons".
Sometimes, when there is a lot of matter squeezed together really tightly, like in a neutron star, the preons can get all smooshed together and mixed up. This is what we call "preon-degenerate matter".
It's kind of like when you have a bunch of toys that you need to fit into a small container. You have to smoosh them all together really tightly to get them to fit.
Scientists are still trying to study preon-degenerate matter and figure out more about these tiny preons!