Unknown Ancient Coin #1 - Caduceus Counterstamp

On Wednesday, August 9, I bought 18 assorted ancient coins (plus one medieval coin), for assorted low prices that averaged out to approximately $2 per coin.
Most of the coins were very worn, and I was unable to immediately identify them (neither was the seller, thus the low price).

I was able to take photos of most of those coins, and will try to post them in this forum for identification (and/or attribution, in cases where I know what approximately it is).

In this case, the most important feature of the coin is probably the caduceus counterstamp (I think it's a caduceus, anyway - too worn to reliably count the snakes).




Note: those are flash photos, which might somewhat diminish their quality.
(I'll try to make non-flash pics later, but I'm not sure I could do decent ones.)

Best I can tell, 12 mm, ~1.6 grams (a ruler isn't a good way to measure weight, but it does somewhat help with diameter).
...And yes, that means the counterstamp is all of four millimeters by two. I won't be surprised if, back when this was in use, the number of snakes wasn't very well visible either.