“Hand-struck, irregularly shaped coins—known as cobs in English and macuquinas in Spanish—served as the primary currency in the Americas for more than two centuries,” Daniela Vargas Ariza, a maritime archeologist and the study’s lead author said in a statement.

Researchers used robotic diving vehicles to study gold coins on the seafloor by the wreck of the Spanish galleon San José.

A wealth of treasure onboard the “world’s richest shipwreck” is starting to be revealed. Marine archaeologists and the Colombian Navy have recently been studying the sunken remains of a ship that's hoped to be the 18th-century Spanish galleon San José.