Ferro Fluid , A Magic Liquid ?

Well , First time i know about this liquid 'cause i've watched discovery channel . Why it makes me so interested ? the liquid can move when a magnet nearby it . In Wiki the liquid called Ferro Fluid. 
A fluid in which fine particles of iron, magnetite or cobalt are suspended, typically in an oil. A ferrofluid is superparamagnetic and can create liquid seals held in position by magnetic fields .

NASA has experimented using ferrofluids in a closed loop as the basis for a spacecraft's attitude control system. A magnetic field is applied to a loop of ferrofluid to change the angular momentum and influence the rotation of the spacecraft. This Liquid Magnet also can be used for cancer detection , used to form liquid seals around the spinning drive shafts in hard disks, etc . .

. . or you can use this liquid to give a pranks , like Freak Encountered  do . . :) i used to watched that episode and get more interested in this liquid :)