Set of 5 Petrified Wood Spheres These spheres look like ordinary stones, but they are in fact incredible objects: they are made of petrified wood, found in Indonesia and dating back to the Myocene, about 20 million years ago. Petrified wood is the fossilized wood of trees buried under a thick layer of volcanic ash. Note. Spheres delivered without wooden bases. Diameter: 6cm, 8cm, 10cm, 12cm, 15cm