Armos are a recurring enemy in the Legend of Zelda series that when approached will come to life and chase link doing damage on contact.
 The Legend of Zelda: Skyward Sword
Armos can only be killed with the Gust Bellows because you need to blow the weather vane-like object on top of its head that will open its mouth reveling two crystals that need to both be destroyed to defeat it. The crystals will only take one shot each but the Armos will become more aggressive and leap at Link fairly fast knocking him down if hit and Link will only have a few moments before it attacks again. One strategy to use it that an Armos cannot leave the room it's found in, so you can hide in a doorway from it to avoid its attacks and wait for the opportune moment to strike (as well as using the Gust Bellows from afar and safety).