 Some of the Olmecs ' rulers seem to have served religious functions . The city of San Lorenzo was succeeded as the main centre of the civilization by La Venta in about 900 BC , with Tres <unk> and Laguna de los <unk> possibly sharing the role ; other urban centres were much less significant . The nature and degree of the control exercised by the centres over a widespread rural population remains unclear . Very fine Olmec art , much clearly made for an elite , survives in several forms , notably Olmec figurines , and larger sculptures such as The Wrestler . The figurines have been recovered in large numbers and are mostly in pottery ; these were presumably widely available to the population . Together with these , of particular relevance to the colossal heads are the " Olmec @-@ style masks " in stone , so called because none have yet been excavated in circumstances that allow the proper archaeological identification of an Olmec context . These evocative stone face masks present both similarities and differences to the colossal heads . Two thirds of Olmec monumental sculpture represents the human form , and the colossal heads fall within this major theme of Olmec art . 
