Liquid magnet

Ferrofluids are composed of nanoscale ferromagnetic particles
suspended in a carrier fluid, usually an organic solvent or water. The
ferromagnetic nano-particles are coated with a surfactant to prevent
their agglomeration (due to van der Waals and magnetic forces).
Although the name may suggest otherwise, ferrofluids do not display
ferromagnetism, since they do not retain magnetisation in the absence
of an externally applied field. In fact, ferrofluids display
paramagnetism, and are often referred as being "superparamagnetic" due
to their large magnetic susceptibility. True ferromagnetic fluids are
difficult to create at present.