Here is an interesting series by the British Museum and the BBC promoting a history of the world in 100 objects, some of which are coins, of course.

Domitianus' reign lasted only a few weeks, and with no literary references to his being emperor, the only evidence for his existence and rule derives from two coins. The first was discovered in France in 1900, the second, now in the Ashmolean Museum, was found in a pot with 5,000 other coins of the period 250-275, thus providing firm provenance, in the village of Chalgrove in Oxfordshire, in 2003.

The design of both coins is typical of those associated with the 'Gallic Empire'. They are of the "radiate" type and depict Domitianus as a bearded figure wearing a spiky or radiate crown representing the rays of the sun, and bearing the legend, IMP C DOMITIANUS P F AUG, an abbreviation for 'Imperator Caesar Domitianus Pius Flavius Augustus'.

The reverse of this coin shows 'Concord', the Roman goddess of agreement, understanding, and marital harmony.Domitianus was probably a Roman soldier of the mid-third century AD who was acclaimed Emperor, probably in northern Gaul, in late 270 or early 271 AD and struck coins to advertise his elevation.