This is a photo of wearing the cap badge of the “Damned Regiment”. The badge is visible between the two buttons on the cap of the captain sitting in the middle. Relatively many photos have been taken of this regiment, and of the variety of their badges. This larger zinc metal badge is also common.
The motif of this is the bayonet surrounded by a laurel wreath, as of the other badges of the regiment. Here, the central motif is complemented by the coats of arms of the Central Powers and their allies. A post about another badge of the regiment can be read here.