Because it's Friday: Ferrofluid

Round out your Friday with a relaxing look at a bizarre substance in action: Ferrofluid.

Basically a suspension of tiny iron particles in oil, ferrofluids produce strange and  beautiful arrangements when subjected to magnetic fields. If you want to learn more about these and other strange materials (and don't mind some not-suitable-for-work language), check out the amusing and informative "7 Man-Made Substances that Laugh in the Face of Physics".