Helmasaurus

The Helmasaurus is a large, leathery-shelled beast that only appears in the City in the Sky in The Legend of Zelda: Twilight Princess. They attack by charging at their victims much like their relatives, the Helmasaur (albeit much more forcefully), and make similar (though deeper) squeals when doing so. However, unlike their smaller and weaker cousins, their durable shell cannot be removed, and may in fact be part of their body.