While her precise identification is unknown, the goddess' association to the sea is confirmed by the rows of undulating waves in the background. A mosaic at Dumbarton Oaks depicts Tethys, the daughter of Uranus and Gaia, with wings in her long hair, while another related work depicts Thalassa, the Spirit of the sea, with crustacean claws emerging from her head (figs. 1 and 6 in S.M. Wages, “A Note on the Dumbarton Oaks 'Tethys Mosaic,’” Dumbarton Oaks Papers 40, 1986). Indeed, the distinction between the two goddesses is not so straightforward: as Wages notes (op. cit., p. 125), the Tethys’ iconography evolved over the course of the 3rd-5th centuries whereby then she is completely merged with Thalassa. Mosaics related to the sea were popular across the Roman empire and were routinely placed in baths, fountains and nymphaea (see p. 77 in U. Pappalardo and R. Ciardiello, Roman Mosaics).