 In species with a wide, open umbilicus, such as the heath snail ("Helicella itala"), the spiral of the whorls can be clearly viewed by looking into the umbilicus.An umbilicus can vary from very narrow and punctured, as found in "Petasina unidentata", to wide and shallow, such as the deep and wide depression in the rounded snail ("Discus rotundatus").Shells with a conspicuous umbilicus are always orthostylic, i.e.