The shell is c. 8 mm in height and up 4.5 mm wide. It has 3 to 3½ strongly arched whorls which are set off from each other by a deep suture. The last whorl is highly inflated, the aperture height occupying about half of the total height. The shell is dextral and relatively thick-walled. The shell is opaque, the surface is matte. The colour is amber on the coast, inland it is rather pale yellowish grey to greenish white in colour. The surface is rough and bears somewhat irregular growth bands. Often the surface layer is camouflaged with dirt or droppings. The animal is mostly grey in colour.
The shell closely resembles that of Quickella arenaria. These two species are separated by anatomical differences: S. oblonga has a long penis with an epiphallus, long vas deferens and no black spot at the insertion of retractor at the penis.
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