Choanomphalus aorusChoanomphalus aorus is a species of freshwater air-breathing snail, an aquatic pulmonate gastropod mollusk in the family Planorbidae, the ram's horn snails, or planorbids.DistributionThis species is found in Lake Baikal, Russia and in Angara River.DescriptionThe width of the shell is 5 mm; the height of the shell is 3 mm.