Snail milk is a type of milk that only appears in the episode "New Digs."
The milk simply looks like ordinary milk from the real world. It comes from sea snails and it makes people fall asleep instantly and quicker. It is best served warm.
Role in episode
SpongeBob drinks snail milk to fall asleep faster after trying everything else in the book that he had read. Within the first few seconds of drinking it, nothing happens. However, after SpongeBob then screams about how he can't go to sleep, the milk makes him go right to sleep.