San Diego Chinese Historical Museum Collection
Click 'original size' viewing option to read interesting description of these stones that reports were naturally formed 270 million years ago.
They have been used as meditation objects for more than a thousand years.

Click http://commons.wikimedia.org/wiki/Category:Chrysanthemum_Stone for more information.

Click http://www.pbase.com/hjsteed/photo_shoot_141219 for more photos of this day's photo shoot at this fascinating historical museum.