Hurricane Balls

Usually sold as a small toy, a very simple device with amazing physical properties.  Also known as tornado spheres (google that to buy some).  This toy is not well enough understood that it warrants scientific publication even in 2015!  The author, David Jackson, is a school friend of Maarten Rutgers.  Apparently you can make them from marbles and glue also.  Investigate!

David also suggested an interesting related puzzle: