Bust represents the Greco-Egyptian deity Serapis, whose cult was founded in Ptolemaic Egypt and spread rapidly throughout the Mediterranean world.
Combining an aspect of Osiris, Egyptian lord of the underworld, with elements from the Greek gods Zeus and Hades, Serapis became a major deity in Alexandria, the principal city of the Ptolemies, a Macedonian dynasty that ruled Egypt during the Hellenistic period.
By the second century A.D., Serapis had become one of the most popular deities in the Roman empire.
Many images of the god took the form of portable busts, suitable for dedication or for private worship.
Silver busts of Serapis are mentioned in an inscription found in Rome (Corpus Inscriptionum Latinarum VI, 30998), but the Museum's work is apparently the only extant example.
The kalathos (Gk.) or modius (L.), meaning grain basket, always shown on the god's head is now missing.