This just arrived from CNG. They listed the counterstamp as "unknown letters". I see it as a dog or wolf but that could just be pareidolia. Any ideas? ATTICA, Athens. Circa 454-404 BC. AR Tetradrachm (22mm, 17.01 g, 9h). Possible eastern imitation. Helmeted head of Athena right, with frontal eye / Owl standing right, head facing; olive sprig behind; all within incuse square; c/m: uncertain letter(s)[?] within incuse square. Kroll 8; HGC 4, 1597. VF, toned, flattened area from countermarking.
awesome!! ... I love counter-stamps!! => yah, I see it as a wolf, or dog as well ... or pig, or turtle (very cool) ... but again, I see lots of cool images in the clouds (I'm just that guy) https://www.google.ca/search?q=pareidolia examples&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwjElZ6Z3qXMAhVqmYMKHY9RAH8QsAQIGw&biw=1280&bih=935 pareidolia ... cool word (thanks for that one => I'm gonna use it at dinner tonight)
Maybe Ardy (from CNG) knows something that we don't know? (nah, I doubt it) ... just jokes my friend (don't get me booted from my favourite auction feeding-hole)
With the possibility of the OP Tet being an 'eastern imitation', that's not as far-fetched as it seems at first
In trying to educate myself, I've been googling various combinations to find information on any ancient counterstamps. I thought "ancient coin wolf counterstamp" was sufficiently generic to give me a few good hits. It's probably not good that my initial post here is the 4th result.
Welcome to the club! Unfortunately, counterstamps on ancient coins are poorly documented. There are some catalogs, like Howgego, but frequently the most we can say is, "These types of marks appear frequently on these types of coins." The why and when of the marks are long lost to us.