Thank you all that have replied back...
Yes, I agree, it is very round and centred - most images of other coins of this type do not have the wheel all the way to the edge of the flan.
However, the condition of the metal looks authentic to me and the existing patina looks real - maybe an ancient fake?
I agree it's strange with the obverse virtually flat, but I think I can see a very faint outline of something (head?) in certain angles/light...maybe I'm just imagining it.
Anyway, I will ID as PROBABLE; "Greek - Thrace, Mesembria AE, Circa 350-300 BC. [Helmeted head of Athena to right] / Wheel with four spokes; M-E-T-A between spokes. SNG BMC Black Sea 278; Moushmov 3977. 1.32g, 12mm.
...Thanks for the welcome John1