Founded in the 7th century AD by the prophet Muhammad, Islam calls its faithful to maintain a strict adherence to certain religious practices, including the Salat, formal worship performed five times a day. Muslims gather to worship in mosques. Each mosque contains a mihrab, or niche, which indicates the direction of Mecca, a holy place. The photomicrograph shown above depicts a microscopic view of ceramic tile. Tile is one of the "clean" materials that may be used to construct the mihrab.