Enough of the legend is present to read -VS GALLVS AVG, so definitely Trebonianus Gallus. Problem is, it's only 15-16mm across, and weighs only 1.31g! Completely normal for the Rome mint in ~268-270, but unheard of in the early 250s! Compare to a "normal" Gallus antoninianus: Radiate "quinarii" were a thing after Aurelian's reforms, but the extremely rare imperial quinarii of this period are laureate: https://www.acsearch.info/search.ht...s=1&thesaurus=1&order=0¤cy=usd&company= (Note that the diameter and weight are right on the money) I'm wondering if this coin is: 1) Some sort of barbarous imitation or counterfeit 2) An exceptional case of negligence at the mint 3) An originally full weight issue that was "clipped" during runaway inflation during the 260s 4) A quinarius flan struck with antoninianus dies Any ideas welcome! Has anyone else seen such an underweight antoninianus from prior to 260?