A ferrofluid is a liquid mixed with small metallic particles that can become magnetized in the presence of a magnetic field. Ferrofluids are used in electronics, spacecraft, and medicine, but are also a fascinating way to visualize a magnetic field in three dimensions. A ferrofluid is known for having properties of two different states of matter: liquid and solid. Whether a ferrofluid is a liquid or a solid depends upon whether a magnetic field is present. Unlike a flower floating on the surface of a pond (where the flower is a solid and the water a liquid), with a ferrofluid the "flower" and the "water" are the same material.
//AZ + TR REVISED