Ferrofluid is a black, solvent-based liquid, that, in the presence of a magnetic field, becomes strongly magnetized. The fluid is made up of nanomagnetic particles coated with an "anti-stick" or surfactant compound, suspended in a "carrier", commonly an organic solvent. For mechanical applications, it is used in hard drives and speakers as a lubricant. However, it also has been implemented in artwork, as seen in the video below.