Shell small, very slender, whorls flat-sided, with three strong cords, cream or light brown coloured at first sight. Protoconch white, two whorls and a nucleus with a diameter of 0,17 mm. On its first whorl appears a spiral angle at the periphery. The protoconch's end is not well defined: the periphery angle descends to form the lower cord of the teleoconch, the other two appearing later. Teleoconch cream or uniform light brown but, under magnification, on this cream colour, small reddish blotches can be seen axially; on the spiral cords these blotches give the impression of a chain-stitch. The whorls arc flat, increasing slowly in size. Their number can reach up to thirteen. The suture is inconspicuous. Three strong smooth cords run all over the shell and after the sixth or seventh whorl, a new cord appears in the suture, in a suprasutural position; it increases slowly in size but it never becomes as big as the three preceding ones. On the last whorl are five cords and a trace of a new one on the base of the siphon. In the interspaces, there are very constant small axial strias. The base is smooth. The aperture is rectangular with the external edge sharp and a little undulating because of the extremity of the spiral cords. The siphonal canal is short and widely open. Dimensions: The single perfect specimen collected had a maximum dimension of 9,3 mm.

By its light colour (cream with reddish blotches), it is different from any of the species mentioned previously. Also, it is larger than any other, except S. angolensis n. sp. Another important difference is the spiral angle of the protoconch which is not present in any of the other Seila species, except also the last whorl of the protoconch of S. angolensis; but this last species has a very different protoconch and lives sympatrically.

S. deaurata n. sp. has only been collected by dredging in Luanda (Angola). S. deaurata n. sp. was found on a sea bottom of rocks and shells at 60-120 metres deep.