a ferrofluid is essentially a liquid magnet. you can make them at home if you're keen, and i assume that's what kim pimmel did to make this interesting macro timelapse video.
"I combined everyday soap bubbles with exotic ferrofluid liquid to create an eerie tale, using macro lenses and time lapse techniques. Black ferrofluid and dye race through bubble structures, drawn through by the invisible forces of capillary action and magnetism."
maybe NASA will one day use something like a ferrofluid as the blood of a robonaut...!?!