English: Ferrofluid, a paramagnetic fluid composed of nanoscale ferromagnetic particles suspended in a carrier fluid, was placed onto a glass plate. The edges of the glass plate are visible at the bottom of the image. A powerful N40 neodymium magnet was placed under the glass along with an iron rod to steepen the field. Spikes form, in a phenomenon called normal field instability, where the magnetic forces are great enough to overcome gravity and surface tension to align the fluid in a magnetically ideal manner.