Book of the Dead
The Book of the Dead is not literally what it means - a book. It is actually a set of magic spells, hymns and prayers. The Book of the Dead was made to help the deceased resurrect into a glorious afterlife through a difficult voyage to the next world.
The Book of the Dead was first read directly off the walls of the inner chambers of the pyramid. Later, it was written on the sides of the mummy cases. The Book of the Dead was found on papyrus, the Egyptian's form of paper. Well-off Egyptians in the New Kingdom would buy a copy with blanks where they could fill in their own names or names of their loved ones.
The Book of the Dead described the ceremonies that took place during a funeral, like opening of the mouth which is an important ritual. This is because the Egyptians believed this would restore the mummy's senses. The process of the weighing of the heart which was the most important moment in a mummy's life was also recorded inside the Book of the Dead.
Ba birds have human heads. The Ba is raising its arms, as if it is telling the mummy's spirit to rise.