No spoilers! Don't spill the beans right away! Here is an ancient coin that took me a while to identify: 21-20 mm. Considering it is pretty clear and the general time period is easy to determine, this one was harder than it looks, and I don't mean you have to find the precise RIC number. If you can get the ruler you are doing well enough. I'll give the identification in a few hours.
The combination of lettering style and the legend and portrait looking less than familiar really makes this an ideal coin for a quiz. The denomination and reverse does help narrow it down to just a couple of rulers.
I have had this coin and went through the painful ordeal of trying to identify it. Fortunately a search for the reverse type gives it away.
Okay, here is the answer. It is a coin of Volusian with an unusual obverse legend IM C V GAL VEND VOLUSIANO AVG minted at Antioch. Antoniniani of Volusian from Antioch are not common and enough different that they can be hard to make out when a few key letters are somewhat encrusted. RIC Volusian 234c, page 185 [Doug cleverly gave the page number which proves he found it.]
