Whilst browsing through a bunch of Carthage coins on offer I noticed the following coin amongst them. I didn't recall having seen one before and so bought it on a gut feel that it was scarce. I hadn't bought a Maxentius since 2004 and now I have bought two in two months.
The only example that I have been able to find online is the one on wildwinds which sold in 2001.
MAXENTIUS, as Caesar. Æ Follis
Obv:- M AVR MAXENTIVS NOB CAES, Laureate head right
Rev:- SALVIS AVGG ET CAES FEL KART, Carthage standing facing, head left, holding up fruits in both hands
Struck in Carthage late 306 A.D. H in left field, Greek_Delta in exe.
References:- RIC VI Carthage 51a.
I believe (quite possibly wrongly) that this is the only time at which Maxentius is referred to as Caesar on bronze coins after his revolt in Rome and before his elevation to Priceps Invictus.
The coin is on a full flan, well centered, with a decent strike and the reverse still holds on to decent detail enhanced by a nice patina.

Martin