Crispus BEATA from London with decorated shield

[Victor]

This coin has an unusual decoration on the shield and I am not sure what it is, maybe just some geometrical pattern.

Crispus
A.D. 323- 324
CRISPV-S NOBIL C; laureate, cuirassed, spear pointing forward, shield on left arm.
BEAT TRA-NQLITAS, Globe set on altar insc. VOT/IS/XX; above three stars.
In exergue PLON
RIC VII London 279