Mucus from the foot glands.
The secretions of these glands solidify when they come into contact with water or air, and thus have the effect of maintaining their shape. In particular, the secretions of the foot glands of the sea snail can form bubbles containing air, and there are many such bubbles attached to the inner surface of the foot in order to make the body float out of the water.
When infested by enemies, its head and feet will retract into the shell, secretion of mucus to seal the shell; when the shell is damaged and failure, it will secrete certain substances to repair the body and shell. Strong patience. Snails have an amazing ability to survive, with a high tolerance for cold, heat, hunger and drought. Prefers to be raised at a constant temperature.
The temperature is constant between 25 and 28 degrees Celsius for vigorous growth and reproduction. When the snail crawls, it also leaves a line of mucus on the ground, which is the liquid secreted by its body. It is not dangerous even if you walk on the edge of a knife.
Expanded Information:
The snail likes to live in a dark, moist, loose and humusy environment, day and night out, most afraid of direct sunlight, the most sensitive to the environment, the most suitable environment: temperature 16-30 (23-30 degrees Celsius, the fastest growing).
Air humidity 60% to 90%; feeding soil humidity about 40%; pH 5 to 7. When the temperature is lower than 15 degrees Celsius, higher than 33 degrees Celsius, lower than 5 degrees Celsius or higher than 40 degrees Celsius dormancy may be frozen or heated to death. But all kinds of snails are different.
Baidu Encyclopedia - Snails
Baidu Encyclopedia - Foot Glands