What happens when matter can’t get any denser yet somehow does? The answer – it becomes “strange.” Strange Stars may be the most massive stellar remnant that is just shy of forming a black hole. And they could be even cooler than black holes.
Neutron stars are made of a substance known as Neutronium. It was thought that this was the densest form of matter possible but some theoretical physicists believe that at the core of some neutron stars the Neutronium breaks down even further, into quark matter. It may even evolve one step further into “strange matter”, the densest and most stable substance in the universe.