The pectoral is a kind of ornament that was very popular or common with Egyptian burials, and they have been found in a large number of varieties.  Tutankhamun's tomb had a number of these and there either used within his mummy bindings or found within chests in the Treasury.

Most have a dorsal ornament which hung down the back, acting as a counter weight and also as a fastening. The piece is built using gold, silver and semi-precious stones and uses cloisonné (for example in the Cartouche). The central element is a scarabs being supported by burial goddesses. The pectoral is a combination of symbolism, mixing moon and sun as heavenly bodies associated with the power of the Egyptian Kings and would have been intended specifically a a burial item.

Egyptian Museum, Cairo.

Tutankhamun's Death Mask and funerary goods. Cairo Museum, Egypt.