Stag Beetle

From Zelda Wiki.org

Stag Beetle
Game(s)	Phantom Hourglass
Habitat(s)	Temple of Ice
Effective Weapons	Sword Grappling Hook

Stag Beetles are mask-wearing monsters that appear throughout the Temple of Ice. These monsters are very similar to Helmasaurs from other games in the fact that they can only be attacked from behind unless you have an item, like the grappling hook, with which you can remove the mask revealing a small insect-like creature that flees away without their mask.