The pillars have four component parts in two pieces: the three sections of the capitals are made in a single piece, often of a different stone to that of the monolithic shaft to which they are attached by a large metal dowel. The shafts are always plain and smooth, circular in cross-section, slightly tapering upwards and always chiselled out of a single piece of stone. There is no distinct base at the bottom of the shaft. The lower parts of the capitals have the shape and appearance of a gently arched bell formed of lotus petals. The abaci are of two types: square and plain and circular and decorated and these are of different proportions. The crowning animals are masterpieces of Mauryan art, shown either seated or standing, always in the round and chiselled as a single piece with the abaci. Presumably all or most of the other columns that now lack them once had capitals and animals. They are also used to commemorate the events of the Buddha's life.