well, not to play on words, but if it's real, it's an 8 reale - cob coin, and it is possible that it was washed ashore. That sort of thing, while rare, is not unheard of at all. It could also be a reproduction, or even a counterfeit fake intended to fool.
Probably the only way to know for sure will be to have it examined in hand by someone familiar with these coins. But if that coin was found "in the sand" - and I assume that to mean a salt water beach - it should show signs of salt water corrosion. And without larger & higher quality pics - I cannot tell if it does or not.
