A death mask is a wax or plaster cast made of a person’s face following death. Death masks may be mementos of the dead, or be used for creation of portraits. It is sometimes possible to identify portraits that have been painted from death masks, because of the characteristic slight distortions of the features caused by the weight of the plaster during the making of the mold. In other cultures a death mask may be a clay or another artifact placed on the face of the deceased before burial rites. The best known of these are the masks used by ancient Egyptians as part of the mummification process, such as Tutankhamun's mask.