Cooooooooool.

[theweaselking]

Supercooled Helium acts as both a solid and a liquid

"Take a bucket of ordinary liquid helium and rotate it slowly, then cool it down to about two kelvins, so that some of the helium becomes superfluid. The superfluid fraction will not rotate. Because part of the helium is motionless, the amount of force required to set the bucket and helium rotating is less than it would be otherwise. Technically, the helium's rotational inertia decreases."