I was in my local coin dealer a few weeks ago, and he showed me a coin he was having trouble identifying. I couldn't identify it at first glance, either, but in my hubris I offered to take it home and identify it for him. "Shouldn't be to hard", I thought.
Boy, was I was wrong.

Here's the coin in question:

The scale is in millimetres, giving the size. It's a tiny little thing, only 10mm by 9mm across and very thick, as you can probably tell from the scans. I don't have a weight yet, but hope to have one on Monday when I take it to work. It's presumably made of silver.
One side, which I shall somewhat arbitrarily label the "obverse", depicts... I don't know. My best guess is a headless human figure of some sort, and that's the way I've oriented it, because I can't see anything recognizable no matter which way I turn it.
The other side has two circular arcs crossing to make a flattened X or curved K shape. It's reasonable to assume that this may be just part of the intended design and there are some missing arcs which would create a trilobe or triple-circle pattern. I think I can see a faint remnant of a letter between the arcs at the top of the picture, but I may just be imagining that.
My dealer friend's best guess was Celtic or Anglo-Saxon, but it looks too thick for that to me.
The "standing figure" may be a very degenerated Sassanian fire-altar attendant, but I looked through zeno.ru at all their post-Sassanian Indian types and found nothing remotely resembling this.
My second guess was later Indian states, something like the fanam listed in
this thread only less stylized. But again, I couldn't find anything that bore more than a superficial resemblance, nothing convincing.
So, after having it sit there on my computer keyboard for several weeks taunting me, it's time to admit the truth. I'm stuck.
Help?
Identified - moved to World Coins forum - SapDon't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis