We all know helium as a gas for blowing up balloons and making people talk like chipmunks. It's also incredibly important as a coolant for medical devices and scientific instrumentation. However, what is less known is that helium has two different liquid states, one of which is truly strange, bordering on creepy.
Helium I occurs between 2.18 and 4.22 Kelvin (that is -270.97°C to -268.93°C ). It has a few quirks of its own. For one thing it is almost impossible to see, so that scientists float things in it just to be able to work out where the surface is. This is a result of being both transparent and barely slowing light at all compared to a vacuum, or the Earth's atmosphere.
However, it's when we go below 2.18K that things get really weird. This BBC video will give you some idea: