my guess is also the 10 lepta as it has no overprint and the 25 has an actual postal cancelation, and you asked which one (singular). After guessing, I did look on internet and found a coin from that era. I remember finding these in junk boxes and always like the design
Comments
Heres the answer:
Yes, I agree DanCong ,those Athean owls look great on coins. Love my silver Tetradrachme 430 BC with the owl on the reverse.