Octogon

In Oracle of Ages, it acts as the Boss of the Mermaid's Cave. It is unexplained why this creature lacks the ability to spit rocks like it's relatives, the Octoroks. It bears a resemblance to Big Octo, who appears in Ocarina of Time.

To defeat this creature, Link stood on the only dry part of the room, tossing either pots or bombs into a hole on Octogon's head whenever he could, and attacking him with his sword if he could manage it. After a while, Octogon would go underwater. Following him using the Mermaid Suit, Link quickly discovered the Octogon was far more aggressive underwater. Despite its aggressiveness, the Octogon finally went the way of the monsters before it, Link overpowering it. Without wasting time, Link then proceeded to take the Lonely Peak.