I like neutron stars better than black holes. In a very real sense, black holes aren’t even part of this universe anymore. Neutron stars are, and what’s particularly cool about them is that light is bent so intensely around them that you can see parts of the other side of them when you’re facing the near side. (Yes, this is also true for black holes, but there’s nothing to see.)

Nuclear pasta is also cool. I want some for armor.