I watched the "Debunked secrets of the Stone Spheres" last night with interest. Have the producers of this show heard of the stone spheres called The Moeraki Boulders on the east coast of the South Island, New Zealand? These were( and still are) being eroded from the mudstone cliffs, some visible in the cliffs, not yet fallen, many on the beach.They are " septarian concretions formed when minerals crystallised in all directions from an organic nuclei".
To me, the spheres in Costa Rica seemed awfully similiar!!!