That's an odd one, I'm not sure what to make of it. The front looks reminiscent of one of those novelty pirate coins (kind of like if someone tried to draw one from memory after seeing one once five years ago) but the unmarked back looks like it might have some actual age to it. Any idea what metal it's made out of? It doesn't really look like a coin to me, maybe a medallion or some sort of decoration off of something? The symbols are interesting, they're a bit reminiscent of some Southeast Asian languages or Arabic writing, but I'm not familiar enough with either to have any clue which language it might be, if those even are characters at all.
I did just notice the outer ring features the same symbol repeated four times, I was thinking it was different symbols at first. I can't make out the inner symbols very well, the new photo you posted is just a lower resolution version of the fourth picture from your first post.
Whatever it is, I'm pretty confident that it isn't currency. But I have a really hard time guessing what else it might be.
It appears to be old (very old). But people reproduce things with that intent nowadays. Is it a spanish dubloon or a cheap knock-off that oxidized real quick because the plating wasn't compatible with the substrate (ie: galvanic corrosion)
How far down was it? Any other interesting items nearby?
For me, I'd take it to a coin shop or post on a metal/treasure detecting forum. But thanks for also posting here, I like seeing cool finds like this.
It's not a coin, it's an occult talisman, that's why it's blank on one side.
Someone probably lost it off a necklace. I believe you can actually see the hole on the back there which must have "filled itself in" while it was left outside.
You will see plenty of these being marketed online as a "mohammedan circle of protection" so it can be very hard to determine the age.
Rear side looks like aluminum oxide. Cant imagine how something that light could work its way down to 9 inches. Could be a casino token. I use a Whites Eagle 2 SL-90 myself.