The sem priest is one of the most visually distinctive figures in ancient Egyptian funerary art, instantly identifiable in tomb painting and relief by the spotted leopard or panther skin he wears draped diagonally across one shoulder over an otherwise plain white kilt. His central duty was performing the Opening of the Mouth ceremony, iunmutef in some of its liturgical framing, a rite carried out on a mummy, a coffin, or a statue standing in for the deceased, in which the sem priest touched the mouth and eyes of the image with a series of specialised ritual implements, most importantly an adze shaped tool, while accompanying recitations declared that the deceased's senses were being restored.
Egyptian funerary theology held that a person's spirit, once separated from the body by death, needed its senses actively reopened before it could eat the offerings left at the tomb, speak the names of the gods, or otherwise function in the afterlife, and that a mummy or statue without this rite performed on it remained inert regardless of how carefully it had been physically prepared. The Opening of the Mouth accordingly stood as one of the single most consequential rites in Egyptian religion, a precondition for everything the rest of Egyptian funerary religion, provisioning, protective spells and continued remembrance, was meant to achieve.