The shell of a Roman snail grows as the snail matures. Proper shell growth requires that the snail be exposed to the right habitat conditions and diet. If temperatures are too hot or dry for the growing snail, shell growth is impeded. Also, if the snail is unable to obtain a diet rich in calcium carbonate, the shell cannot grow.
Roman snail shells typically have four to six whorls. The umbilicus (the circular space on the underside of the snail's shell located at the center of the whorls) is narrow and partly covered by the columellar wall.