Snails can enter a state of dormancy called estivation (summer sleep) or hibernation (winter sleep) that allows them to survive extended periods of unfavorable conditions, potentially lasting up to 3 years. During these periods, their metabolic rate drops dramatically, and they seal themselves inside their shells using a mucus membrane called an epiphragm to prevent water loss. This adaptation enables snails to survive drought, extreme temperatures, and food scarcity. While 3 years represents the extreme upper limit, most snail dormancy periods last much shorter durations.