Canopic jars were used to preserve the internal organs of the deceased and were buried with the mummy.  They always come in groups of four, with each animal meant to hold a specific organ.

Jars in the form of a baboon (Hapi) held the lungs.  Hapi is associated with Nepthys, who was a protector and guardian goddess and helped her sister, Isis, reassemble the parts of Osiris's body after he was murdered and thrown into the Nile.