The bas-relief in flowered alabaster (stone of great value from western North Africa) arrived in the Museum in 1768 following the purchase of the collection of the Jesuit Luigi Canonici. Perhaps coming from Rome, it must originally have been the umbilicus of a circular basin with a diameter of about two meters.

The highly stylized antennae or crayfish legs protruding from the subject's head allow him to be identified with the god Oceanus: non-personified origin of all things in the Homeric Iliad, pater rerum and creative force of nature in Virgil, limit of human space , Ocean maintains a privileged relationship with the stars, being the element in which they set and from which they rise again; it precedes the generation of the Olympic gods and represents the fruitful force of flowing water, which uniting with Teti has generated Uranus (the sky) and Gea (the earth) and which feeds all the seas, rivers and springs. As a symbol of fecundity, rebirth and limitation of the known world, Oceanus becomes part of mystery cults of oriental origin, as an image of the vastness of the Roman empire, it falls within the political symbology of Augustus, but it is in the Severan age that the representation of the god knows its greatest diffusion.

Stylistic comparisons allow us to date our bas-relief between the end of the 2nd and the beginning of the 3rd century AD: its iconographic model comes from Egypt and is relaunched in the West by the portraits of the emperor Septimius Severus.