Top voussoir in arch or in some types of vault, usually moulded and decorated with carved decors, made of stone or ceramic, characteristic of gothic rib vaults. It is located at the highest point of the vault or arch. Usually slightly larger than other stone or brick elements. At first the bosses were not adorned. Only after the introduction of the rib vaults, at the site of the intersection of the ribs, these places were accented by a stone plate decorated with a coat of arms, a mask, a figurine sculpture or a whole ensemble of such sculptures.