The sphericon

An interesting shape that one of my friends in high school experimented with. It has some interesting properties, most specifically a highly irregular wobbling roll that still travels in a straight line.

Here is the site by the creator of the sphericon:

http://www.pjroberts.com/sphericon/history.php

and here are instructions to make one out of clay, in case anyone was interested:

http://www.instructables.com/id/Make-a-ceramic-sphericon/