This relief shows various musical instruments hanging from a nail. They include a violin, pan pipes, lyre, recorder, harp and bagpipes. A celestial globe is also depicted, along with an armillary sphere, sheet music, anatomical and botanical drawings and laurel wreaths.
Additional information:
The celestial globe and armillary sphere allude to Apollo as the sun god driving his chariot across the sky from east to west, while the musical instruments and sheet music refer to his role as the god of music, poetry and art.