Each TUFA sculpture is created with a material called Hypertufa over empty wine bottles.  Most have a removable hat or head-dress.
Hypertufa is made from equal parts portland cement, peat moss, sand, vermivulite and water.
It's a chunky material and I love it's rough feel over the smooth surface, of the bottles. Since it's impossible to paint fine lines over the surface, they tend to have a chunky, tribal, voodoo antiquity with a quirkiness that makes me laugh!