In Islamic architecture, the dome and the cubic space underneath are joined through the creation of moqarnass. The innovative space of moqarnass resembles the relation between heaven and earth. The dome symbolizes the heaven and the cubic space underneath it represents the earth, and the moqrnass arches regarded as the linking point between heaven and earth. Moqarnass is considered a technical element in architecture besides its role as an ornamental element. 

Moqarnass shapes in Islamic architecture were employed first in the corners and angles of domes. Originally, when they wanted to erect the enormous building of domes, they required some technical factors in order to prevent the collapse of the heavy roof of the dome because the domes in Sassanid era collapsed due to lack of necessary strength and resistance. As mentioned above, Muslim architects came up with some unique technical and artistic innovations, which were unprecedented in the world of architecture through the application of dome-shaped ceilings and adopting the styles of earlier architecture.
They divided the ceiling of the dome, which rested on a square-shaped base in Sassanid era, into hexagonal and octagonal bases and eventually positioned the dome upon octagonal bases; therefore, the pressure exerted by the dome-shaped ceiling, which was transferred to octagonal side corners, prevented the collapse of the dome. These octagonal angles appeared as small triangles whish also served an ornamental function. Afterwards, in later stages the art of moqarnass became widespread using flexible materials such as plaster.
Thus, the most prominent ornamental element in Islamic decorations is moqarnass, which is reminiscent of the frozen rocky façade of stalagmite in caves. Moqarnass also bears a great resemblance to honeycombs, which are built one over the other for arranging the buildings or for gradually changing from geometric shapes into other shapes, and especially from square shapes to circular shapes on which the domes are rested. In constructing the moqarnass, Muslim architects have become so adept that they prevent the building from becoming heavy, putting the pressure instead on the base of the building. Moqarnass leads to the equilibrium, solidity, and strength of the building, and looks as if it were the roof of the sky that rests on the cubic volume of the earth. Moqarnass, which is itself a kind of intermediary shape (it is neither ceiling nor side wall) has been able to provide the magnificence, grandeur and spirituality of the sacred building and it could also be considered as an element that refers to matter and spirit, that is, the movement from the square of the earth towards the circle, or the central point of heaven, which suggests that heaven descends to earth, and earth ascends to heaven in geometric and crystal shapes of moqarnass, and human being is positioned in between.