Asta Bidspirit | A roman carnelian intaglio. Sea

A roman carnelian intaglio. Sea scene. 2nd - 3rd century A.D. 8 x 9,5 x 3 mm. Rare and unusual representation of a character with an oar (or rudder, or scepter?) that comes out of a shell. Small chips on the edge. Probably from the marine Thiasos of Poseidon. Provenance: UK private collection.