Lynn V. Foster reports that pearls have been found in Maya ruins.
Lynn V. Foster, Handbook to Life in the Ancient Maya World (New York: Oxford University Press, 2002), 10-11
Precious Objects and Artifacts
Many types of objects have been recovered from tombs, household mounds, and dedicatory caches in buildings and sacred wells. Jade, serpentine, and, by the end of the Classic Period, turquoise were among the most precious materials to the Maya. Stingray spines, used by royalty as bloodletters, orange-red Spondylus shells, and pearls were also items precious enough to accompany wealthy Maya in death. Many of these items were carved into ornaments and made into jewelry. Obsidian, iron ores, and gold were polished into mirrors, probably used for divination and visions as well as for more mundane purposes. Gold and copper objects are found primarily after 800 C.E.; gold was shaped into luxury items, but copper was also made into practical ones, such as fishhooks and needles. When these items accompany burials, they usually indicate wealth and status. They also tell us about Maya dress, Maya social classes, and mortuary rituals and religious beliefs. Furthermore, they indicate trade among pre-Columbian peoples: Turquoise, for example, was traded from what is now the Southwest of the United States.
There are many other materials retrieved from excavations, among them are cinnabar, obsidian, chert, mica, and crocodile hides, as well as the rarely surviving pieces of wooden sculptures or fabric. Carved animal bones—and carved human ones, perhaps kept as relics of a famous ancestor or a trophy of a war victory—are also found in graves. Although obsidian could be carved into elaborate objects worthy of a tomb, it was also used for razorsharp tools. Many such artifacts, shaped and formed and treasured by the Maya, can be carefully identified through various techniques—X-ray flourescence spectronomy (XRF) and atomic absorption spectronomy (AAS), for example. Such techniques can identify the origin of materials such as obsidian, providing further evidence of trade patterns among the Maya and their neighbors; some techniques, such as obsidian hydration, can assist in dating the artifacts. Even when technology cannot reveal the source of materials—or dat them—careful excavation often can. Most tools were made of chert and flint, and debris from these materials may indicate artisan workshops and worker specialization; Colhá, located near a source of chert, was an important Preclassic city.