piece of eight

This is a Spanish 8 Reale I found while mudlarking. It was minted in New Guatamala in 1808 and bears the bust of Charles IV.

I've been collecting artifacts from Robert Marx's excavation of Port Royal and bought 2 coins from a reliable source. He said he purchased them directly from Bob Marx. While I was reading through his books, I noticed that one of the coins I purchased seemed to have been used in several of his...