Spondylus, the thorny oyster and Francisco Pizarro's 1525 expedition.

The very first European account of the lands of the Inca Empire describes a trading raft laden with riches. In 1525, Francisco Pizarro's expedition encountered the indigenous sailing craft off the coast of Tumbez, just south of the equator. Filled with objects of gold and silver, including crowns, diadems, belts, bracelets, leg ornaments, and breast plates, the raft's cargo also included emeralds, crystal, and amber, as well as many elaborately decorated and richly worked garments made from wool and cotton. To the astonishment of the Spaniards, these fineries were traded for coral-colored seashells, undoubtedly spondylus, a marine bivalve known as the thorny oyster.