The state of mythical calmness

It’s a place made out of earth, with many corridors and caves, full of mud and sand. The Mythical Creatures spend most of their time in a state of calmness, being almost half-asleep. Only in very few occasions, the Mythical Creatures break out of their calm state in order to engage themselves in stormy and ferocious, incomprehensible activities of varied duration. Nobody knows why and when exactly these activities take place, but it is strongly recommended to avoid any actions that might wake up the Creatures from their State of Mythical Calmness.