I've been reorganizing my coins and figured I'd try this one again and grabbed some slightly better shots of it. its about 18 mm, AE and sunken in on the rev. Maybe alexander III on obv.
also thought I'd post this too, not a coin and most likely not ancient, but came with in a lot of uncleaned ancients. was faily crusty so I can see how it got mixed in. about 20 mm bronze