piece of eight 
noun historical
A Spanish dollar, equivalent to 8 reals.Spanish piece of eight, a coin common in the American colonies during the Revolution, had eight segments marked on their reverse so that the coins could be divided (to make change)....
- My senses were all confused as within my sight was a king's ransom - Spanish gold doubloons and shining silver reals, gold pieces of eight, old English milled gold guineas, crowns, minted silver shillings.
- I changed all my available funds into copper pennies - the old ones, the size of half-crowns - which I would trickle through my fingers as if they were doubloons or pieces of eight.