[1] In general, rugae are a biological feature found in many organisms, serving purposes such as increasing surface area, flexibility, or structural support.

For terrestrial gastropods, the rugae often appear as fine, transverse folds or wrinkles on the mantle, back, or sides of the body.

A purpose of the gastric rugae is to allow for expansion of the stomach after the consumption of foods and liquids.

This expansion increases the volume of the stomach to hold larger amounts of food.

The folds also result in greater surface area, allowing the stomach to absorb nutrients more quickly.