About Steromphala umbilicalis (da Costa, 1778)
The adult shell of this species measures between 10 mm and 22 mm in size. Compared to the shell of Gibbula cineraria, this species' shell is more depressed, never develops a pyramidal shape even though its base is flatter. Its spiral ridges are sharper and less numerous, particularly in young individuals. The two species have similar types of markings, but their overall colouring differs. In this species, the longitudinal streaks (or rays) are red, broader, and far fewer in number than those of Gibbula cineraria. The longitudinal streaks are sometimes zigzag, rather than broken into spots or interrupted by the shell's sculpture. This species can be described as striped, while Gibbula cineraria is lineated. Just inside the outer lip of the shell are two borders: one is yellow, and the other is green with red spot variegation. This bordering is covered in fine small tubercles, giving it a shagreen-like texture. This is a marine species that occurs in European waters and in the Mediterranean Sea off the coast of Morocco. It lives from the upper shore down into the sublittoral zone, on sheltered rocky shores, and tolerates periods of emersion and brackish waters.
