Miniature art includes paintings, engravings and sculptures that are very small; it has a long history that dates back to prehistory. The portrait miniature is the most common form in recent centuries, and from ancient times, engraved gems, often used as impression seals, and cylinder seals in various materials were very important. For example most surviving examples of figurative art from the Indus Valley civilization and in Minoan art are very small seals. Gothic boxwood miniatures are very small carvings in wood, used for rosary beads and the like.