Do this at home:  Researchers have stumbled upon a unique state of matter by dropping a marble into sand.  The impact of the marble against a dense arrangement of particles produced a "jet" of sand into the air like a tall, thin spike--as if the sand were fluid.  These scientists have determined that air in between the tiny sand particles is compressed upon impact, creating an active, fluid-like state.  Two photo sequences show the experiment when tested in a vacuum, and when tested without one.  The jet in the vacuum is almost non-existent.  The researchers say you can conduct a small version of this yourself by dropping your own marble into a loosely-filled cup of powdered sugar.  There's no way no one has ever observed this phenomenon before.  Don't you wish you had helped your mom out more in the kitchen?