Cassolette Stone

• Cassolette Stone
  Iwami-gun, Tottori-ken, Japan
  
  These stones are not man-made. It is an artwork of nature.
  First, cracks occur in all directions in shale stratum. Then, iron dissolved by rainwater in the upper stratum penetrates into the lower shale stratum and fill in the cracks. Iron solidifies and forms small shale blocks.