Often considered to be the “mother culture” of Mesoamerica, the Olmecs flourished between 1200–600 B.C.E. in present-day Mexico. The Olmec society left behind no written language, but their monumental art indicates that the culture was highly stratified, with clearly defined social classes. The colossal heads found at San Lorenzo in Veracruz are one of the most recognizable monumental art forms in the Americas. Made of basalt, the colossal heads weigh between five and twenty tons each. Up to eight feet tall, the heavy-featured sculptures have broad noses and thick lips. The heads wear helmets with earflaps and straps under the chin. Scholars believe they represent rulers or historic figures important to the Olmec culture.