Muquarnas

Muquarnas, or honey comb vault, is a traditional Islamic decoration developed at the beginning of the ninth century.
Muquarnas ("honeycomb vault" or "stalactites") is one of the most essential elements of all classical Islamic architecture. This is a presentation of three-dimensional structures made using concave elements, which are assembled according to complex geometric rules. In Moroccan decoration, we use plaster or wood to produce Muquarnas.

The use of Muquarnas, especially in plaster, reached an extremely high level of sophistication in Andalusia. At the same time, the scale of Muquarnas was relatively reduced. Muquarnas units have, however, been constant in Islamic architecture since the 9th century.
Muquarnas spread throughout the Islamic world in the late 11th century. It has been and is used in corners and domed rooms, and to decorate corbel arches, capitals, archways, cornices, and even walls, as simple, eye-level friezes.