Pieces of Eight

From Monkey Island wiki

Pieces of Eight are the default currency in the Monkey Island series. They are derived from the actual historical Spanish dollar. They became a popular form of currency between 15th and 19th centuries and have been used as legal tender in many countries, due to the high number of Spanish colonies. The Spanish dollar reached the peak of its popularity in use during the 18th century and was still used as a legal tender in the United States until 1857.

Contrary to its depiction in the Monkey Island series, pieces of eight were minted from silver and not gold. The term piece of eight refers to their relative value to the Spanish reale, eight dollars making one reale.