Also called an aes.
A copper Roman coin (as singular, asses plural). These are slightly larger than the dupondii. On asses the Emperor's head is shown wearing a laurel wreath. Two asses were worth the same as one dupondii.
The obverse of a Roman as coin from the site of a Roman temple in Caistor St Edmund. NWHCM 1929.152.11:A
(© NCC)