License, verbatimCC0
The Metropolitan Museum of Art: Open Access, Creative Commons Zero (CC0). Flagged isPublicDomain=true in the museum's own record.
Giovanni Jacopo Caraglio. Plate 5: Neptune standing in a niche holding a trident, with a hippocampus (sea-horse) behind him, from a series of gods and goddesses, 1526. The Metropolitan Museum of Art.