Coins have been used as a form of currency across the world for almost three thousand years. Much like today, the earliest coins were formed from metals, with more precious metals reflecting higher monetary value. The most common shape of coin is a flat, rounded disc shape, which also tends to be small in size. Antique and rare coins can hold high value on the collectors' market, and some coins produced by Spain can be of particular interest to numismatists. First minted during the height of Spain's power in the 16th century, the doubloon was a coin crafted from 22-carat gold and became one of the coins hoarded by pirates as treasure; as a result, Spanish coins have been salvaged from shipwrecks worldwide. A few years ago, a rare Tricentennial Royal coin was found off the coast of Florida, worth an estimated $500,000.