Turtle Rock (Boss)

The Turtle Head is a mini-boss in Link's Awakening, and its Game Boy Color remake, Link's Awakening DX. At first it is actually a part of the Turtle Rock dungeon, where it is actually made of stone and is blocking the entrance to the dungeon. However by playing the Frog's Song of Soul, the head will 'revive' and will try to attack Link by swooping down at him. Once Turtle Head is defeated though, the entrance to the dungeon becomes and remains unblocked.

Trivia

 * So far, Turtle Head is the only mini-boss in the series that is directly right before a dungeon.