Gekko

A Gekko (ゲッコー, Gekkō) is a possessed frog-like mini-boss that guards two of four temples in Majora's Mask.

The first one is found in Woodfall Temple. It rides the back of a giant Snapper. Once the Snapper is killed, this creature will run along the walls of the room. Link must shoot it with his bow in order to defeat it.

The second Gekko, found in the Great Bay Temple, will hang to the ceiling in a bubble of Mad Jelly. A simple Ice Arrow will freeze him inside, sending the Gekko sailing down to the floor. If Link fails to shoot the Gekko, or gets to close to the bubbles, he will be trapped inside. The Gekko will then punch Link repeatedly causing damage. It then finishes it off with a mighty left hook, that breaks Link through the bubble, causing serious damage.

After Link defeats each of the amphibious creatures, they will turn into one of the frogs from Don Gero's Frog Choir.

Trivia

 * The Chu Worms, which appear in the Lakebed Temple and the Cave of Ordeals in Twilight Princess, is similar in some way to the Gekko and Mad Jelly.
 * Though it's name is a corruption of the word gecho, it bears more of a resemblance to a frog.