Why wasn't the heart removed from an Egyptian mummy's corpse?

The heart was left in a deceased Egyptian because it was thought to store the person's personality, emotion and memory. It was the only major organ left in the body at the time of mummification.

By today's standards, the Egyptians had an odd way of burying their dead. The eyeballs of the deceased were pushed into their sockets and at times, replaced by onions. Padding was sometimes added to arms and legs to make them appear less shriveled as they dried and the fingernails and toenails were removed and tied to the corpse so they didn't fall off. Organs like the liver, kidneys and lungs were removed and placed in a canopic jar and the skin was moisturized to keep it from drying out.