Maxentius, AE Fraction, 306-312 AD. Rome. 

Obv: MAXENTI-VS PF AVG, head right, wearing lion's skin headdress
Rev: VOT X FEL B within wreath.
RIC VI 241 note 3; CNG Coin shop item 731608

Extremely rare variety.
$425.

The mintmark 'B' that appears on this coin is enigmatic, as the normal 
mark for this issue is RP-Q. RIC does not speculate upon it, but notes 
that the only specimen found was at the ANS (catalog no. 1944.100.3016). 
A second specimen, in Good VF condition, was sold at auction (Classical 
Numismatic Group Sale 46 (24 June 1998), lot 1429), with a hammer-price 
of $520. The present coin is therefore the third known example.

Used with permission of CNG coins, www.cngcoins.com, Jan. 2011