Umbonium costatum is a species of sea snail, a marine gastropod mollusk in the family Trochidae, the top snails.[1][2]
The size of the shell varies between 12 mm and 25 mm. The heavy, solid shell has a depressed shape. Its spire is low-conoidal, the periphery rounded. The color pattern is whitish or light yellow, closely tessellated all over with blackish-olive or reddish-brown squarish spots. The tessellated color-markings sometimes form subcontinuous oblique bands. The surface is shining and polished, with strong spiral grooves above, generally 4 to 6 on the body whorl. The sutures are narrowly impressed, with a rather wide margin below them, which often shows a slight tendency to be tuberculate. The base of the shell is smooth, tessellated around the irregularly convex, flesh-colored central callus. The shell contains six whorls, the last a little concave above, convex beneath. The subquadrate aperture is pearly inside. The circular callus is heaviest in front of the aperture and behind the columellar lip. .[3]
This species occurs in the Sea of Japan and in the East China Sea.
Umbonium costatum is a species of sea snail, a marine gastropod mollusk in the family Trochidae, the top snails.
