I found this article about teeth (I knew I read this somewhere)

Food Habits

Brown snakes feed largely on earthworms, snails, and slugs, but will also eat small salamanders, soft-bodied grubs, and beetles. They have specialized teeth and jaws that allow them to pull snails out of their shells and eat them. (Ditmars, 1936; Harding, 1997)

http://animaldiversity.ummz.umich.edu/site/accounts/information/Storeria_dekayi.html

Maybe mine isn't hungry enough yet, it looked and got close. There are small and large snails. There is moss, mulch and soil and the snails prefer the plexiglass top and glass sides.