This is part of the lid of an outer coffin.
It is from Alexandria, Egypt. Usually, the richer a person was, the more elaborate their burial. A mummy could have one coffin, or a nest of coffins. This is half of the lid of an outer coffin from a mummy buried in two coffins. One of the final acts of burial was for the mummy to be sealed into its coffin or coffins, and placed in the burial chamber. Food and ritual objects were piled up, and priests made sure no evil spirits lurked in the tomb. This is part of the lid of an outer coffin. It is made from wood. It is over 2,500 years old, dating to the 26th Dynasty (664-525 BCE) in the Late Period.