unusual I'd imagine to find a bowl without a single curved line in the shape or design - it was the pure deco looks that appealed to me.
Octagonal - if that's correct for an eight sided shape - and with small amount of pressed design to the otherwise flat underside. About 7.25" (c. 185 mm) diameter from flat side to flat side.
I've looked at Pamela's glass-pavillon without success, but lack the courage to start on the musterbuchs, and hoping someone will recognize the shape and save me the trouble, please

Age wise I'd plump for 1930's but really not sure.