Neat find! Hope it's real. In my antique mall dealer days, I had someone bring me what purported to be a cob 8-reales coin that he said had been found on the beach here (St. Simons Island, GA). It did have some sand in the crevices, but it was a total tourist fake and not even silver. I did believe the guy's story about finding it on the beach, however. (But it's also possible his story was as fake as the coin.) An old friend of mine did find a genuine (small-denomination) cob on the beach here. And there have been other Spanish Mission Period artifacts found here- this one by another friend of mine, and this one by me.
This is a tricky one. On the obverse, on the left hand side of the coin, I can clearly see the letter S, which suggests that it came from the mint at Seville. At the same time, while I can make out the arms of Spain (1st), quarterly, the arms of Castille and Leon; 2nd, the arms of Aragon Impaled with the arms of the Two Sicilies; 3rd, party per fess (that is, split across the middle), the horizontal red , silver and red stripes of Austria and underneath that , bendy (diagonal) stripes of Burgundy), the coins is too worn to be able to make out the 4th quarter, but this is probably the “abbreviated” coat of arms adopted by Carlos I of Spain before he became Holy Roman Emperor in 1519 as Carlos V of Germany. Why abbreviated? Check on these two links to see his full coat of arms and the abbreviated version: https://es.wikipedia.org/wiki/Escudo_de_Carlos_I_de_España https://es.wikipedia.org/wiki/Escud...dia/File:Armoiries_empereur_Charles_Quint.png The arms on this coin do not belong to Carlos I as the coins with his name on (those of Juana, his mother, and Carlos) use the simple arms of Ferdinand and Elizabeth and with one exception; no coins were issued in the name of Carlos, the exception being coins from Mallorca which show only the arms of Aragon. So these are the arms used by Felipe II from the date of his accession as King of Spain in 1566 up until 1598 when the arms of Portugal were added in an inescutcheon (a small shield placed in the top middle of the Spanish arms). It is too heavy for 8 reales, and too light for 2 reales, so it looks pretty clear to me that it is a Seville hammered 4 reales coin (original weight 13.7 gms) which has been slimmed down as much by the sea as by usage.
