Helium is a very strange beastie. With most elements, if you cool it down enough, it will turn into a solid. The molecules will slow down, and then lock into place. But helium does very strange things when you cool it down enough, including refusing to solidify as you approach absolute zero.

Of course, this is all the fault of quantum mechanics, which has the somewhat annoying property of being totally counterintuitive and also matching all experiments to see whether it’s true or not. At the atomic level, things are just weird.

Some of the weird things that helium does when you get it cold enough, cold enough to turn it into a superfluid, are: climb up walls, fit through microscopic cracks that it can’t fit through as a regular liquid, and make a superfluid fountain.