Based on the information provided, the digestive system is a key component located within or associated with a snail's shell.
The reference indicates that the snail's digestive system is situated, and that its location is next to the breathing hole. This anatomical arrangement means that feces are expelled in this area, near the snail's opening.
While a snail's shell houses many of its vital organs and the main body mass (visceral mass), the provided reference specifically highlights the presence and orientation of the digestive system within this protective structure, noting its function in waste expulsion relative to the breathing apparatus.
