This example shows the use of the Magnet SOP, and illustraites its ability to deform geometry.
The Magnet SOP works by using the Density Field of a Metaball as a Magnetic Influence Field on a piece of geometry. The degree to which the Magnetic Field effects the surface it is deforming is based on the distance of that surface to the center of the Metaball.
Here, the Metaballs have been attached to a moving particle system which bounce across a plane. The Metaballs also interact with the plane, causing it to bubble upward as their Fields intersect the surface.