Normally the meristematic cells are oval, polygonal or rectangular in shape. Domes over windowed drums of cylindrical or polygonal shape were standard after the 9th century. It is a conic solid with polygonal base. Where keeps did exist, they were no longer square but polygonal or cylindrical. Modeling tools allow the generation of polygonal or NURBS models. Ancient circular or polygonal churches are comparatively rare. They can be ovate, polygonal or angular. The chancel and transepts are of identical polygonal plan, separated by two smaller polygonal chapels. Laplacian smoothing is an algorithm to smooth a polygonal mesh. ACP barrels deviate from the other models having polygonal rifling instead. The barrels could have traditional rifling or polygonal rifling. The Desert Eagle's barrel features polygonal rifling. A cone with a polygonal base is called a pyramid. A consists of one point by edge of a polygonal cone. Other methods also exist for describing polygonal tilings.