muqarna
Decorative device in Islamic architecture, like a small pointed niche, used in tiers projecting over those below, usually constructed of corbelled brick, stone, stucco, or wood. Applied to cornices, pendentives, squinches, and the soffits of arches and vaults, with their scalloped surfaces and pendants they present a very rich sight when seen from below, sometimes resembling stalactites… (Curl & Wilson, 2016)