Deuterium Dioxide!
How to destroy a galaxy...
Q: What is Deuterium Dioxide?
A: It's heavy water!
Q: No really, what is it?
A: It's an isotope of hydrogen combined with oxygen
Q: Ok.... so what is it used for?
A: It's used as a moderator (slows down the neutrons) in a nuclear reactor
Q: And what are these pictures?
A: Ah, it's frozen deuterium dioxide (sinks in normal water)
