Interactions
Columella simplex does not interact with many species, but it has predators and possible competition for resources. It has a few predators including salamanders, other land snails, and small mammals (Discover Life In America). As for interacting with other snails, Columella simplex was found living near snail species such as Discus catskillensis, Punctum minutissimum, Zonitoides arboreus, Strobilops labyrinthica, Anguispira alternata, Vertigo gouldi, Striatura milium, Helicodiscus shimeki, and Euconulus fulvus (Nekola, 2002). All of these species could be considered competition to Columella simplex in terms of breeding sites, food, and habitat in general.
One interesting fact is that Columella simplex is often mistaken for Columella columella in the southwest of the United States (Nekola & Coles, 2010). This is apparent in the obvious similarities in their shells as shown below. The main difference is that Columella columella can have up to 7.5 whorls and its shell can be wider than that of Columella simplex (Schultes, 2006).
Columella columella shells Columella simplex shells