The censer is often called a thurible and used during important offices (benedictions, processions, important Masses). The common design for a censer is a metal container, with holes on top, a bowl underneath, suspended on chains. The bowl contains hot coals, and the incense is placed on top of these. The censer is then swung back and forth on its chains, spreading the fragrant plumes. The boat is the container for incense to be burned in the censer.