This is an air-breathing land snail with a strangely structured aperture that gives it its name, Labyrinthus. Some of the species apertures are even more deeply notched. I wonder what function they serve.This shell is about 1¾" across and about ¾" high, dark brown with a white line girdling its widest point.
This labyrinth snail and an apple snail were found at the verge of a manmade pond in the rainforest along the Amazon River.
I included my sketch because it clarifies the structure in the mouth of the shell.