During the process of mummification, the soft internal organs of the deceased were removed, individually preserved and placed into separate vessels termed canopic jars. When the deceased was symbolically resurrected in the hereafter, the internal organs were believed to function within the body to which they were magically returned. This practice began during the late Fourth Dynasty onwards, when sets of four canopic jars formed an important part of the burial equipment that accompanied the mummy. The jars containing the viscera were used in the tombs of kings as well as those of high officials. The simple lids customary during the Old Kingdom period were surmounted by human heads in the Middle Kingdom and the Eighteenth Dynasty of the New Kingdom. From Ramesside times onwards they were made in the form of heads representing the Four Sons of Horus, the so-called canopic genii, each of whom were responsible for a particular organ:
Imset: Human-headed (liver)
Hapy: Baboon-headed (lungs)
Duamutef: Jackal-headed (stomach)
Qebekhsenuef: Hawk-headed (intestines)
Inscriptions on these jars show that each of the four was under the protection of a goddess (Isis, Nephthys, Neith and Selket, respectively).