Costa Rica has presented a bid for its pre-Columbian stone spheres to be inducted into the exclusive World Heritage list by the United Nations Educational, Scientific and Cultural Organization (UNESCO). Cultural or natural sites or monuments can make the list if UNESCO deems them to have “outstanding universal value,” according to the international Convention Concerning the Protection of the World Cultural and Natural Heritage.

Experts in archaeology, art and other fields visited several sites in the Southern Zone last week, where many of the spheres, of varying sizes, have been discovered.

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Regarded as indigenous treasures, hundreds of the almost perfectly round monoliths have been spotted in different parts of the country since the 1940s. Today they can be seen in gardens of government buildings and private homes. Many are no larger than a bowling ball. Some are larger than life, such as 15-ton boulders. They're usually made of granodiorite, a hard, igneous stone similar to granite. Archaeologists believe native inhabitants chiseled, pecked and ground granodiorite boulders using rocks of the same material to create the spheres.

Archaeologist Francisco Corrales said the carved stones reveal much about the Costa Ricans' pre-Columbian ancestors.

“The finding leads us to believe that these spheres were symbols of social prestige and hierarchical positions” during the Chiriquí period from 800 to 1500 AD, Corrales told The Tico Times. The Chiriquí were ancestors of the Brunca, one of Costa Rica's eight indigenous groups.

“This is important because it reinforces the fact that they (the spheres) were created by indigenous people who had a complex society, capable of constructing such things. (The Chiriquí) were experts with stone,” he said.

Freddy Montero, cultural program officer for UNESCO's San José office, said the recent visit is the start of a long and important process.

"It's not as though UNESCO arrives, declares world heritage and leaves," said Montero. He explained that the greatest value of this first step is it should encourage a process on a national and local level to work to improve research and preserve the spheres.

UNESCO representatives seem interested in the uniqueness of spheres. Nuria Sanz, who visited from UNESCO's World Heritage Center in Paris, France, told the newswire EFE that she's aware of cultures that also work with this form but "not in the same context or crafted in the same way" as the Costa Rican spheres.

Montero, who is liaising between the Paris office and the National Museum in San José, said the experts are drawing up recommendations for a work plan that would carry the Costa Rican spheres onto the coveted heritage list. For Costa Rica, he believes this process will prove even more important than the world heritage declaration itself.

No timeline has been set yet, but Montero acknowledged that in the past UNESCO has committed up to 10 years to working with national governments and local authorities to meet standards of preservation and research. The time it takes depends on how well a country has prepared before presenting its bid to the World Heritage Center. In Montero's eyes, Costa Rica has invested much in researching its spheres but "there's still a lot of work to be done."