Froshell

It anchors itself firmly to cold stone and seals within its crystalline shell, and there it waits, motionless for weeks, as the larva within remakes itself into the moth to come. The shell is genuinely hard, armored against cold and predators alike, and a Froshell will endure being knocked about, frozen over, and buried in snow without stirring. It is not, however, wholly helpless; disturbed too roughly, it can loose a burst of frigid air from vents in its shell, a cold enough shock to make most predators leave the strange glittering thing alone and go find easier prey.