NZMS coloring ranges from tan to dark brown, and specimens stored in ethanol may turn white. Their length ranges from 3.5–6 mm in invasive populations (Ponder 1988, Zaranko et al. 1997), while reaching up to 12 mm in their native range (Winterbourn 1970). Juveniles are much smaller. NZMS is longer and narrower than most native snail species in the Great Lakes region, and their opening is always on the right side when facing the snail towards you. They have between 3 and 8 dextral whorls, with most having five or six. A keel may be present mid-whorl. It should be noted that the variability of NZMS morphology is influenced by both environmental and evolutionary forces (Proctor et al. 2007, Kistner and Dybdahl 2014, Verhaegen et al. 2018); as a result, NZMS from different lineages, habitats, and ranges may look different.