Digdogger

Digdogger (デグドガ, Degudoga) is a recurring boss in the Zelda series, appearing in both the original The Legend of Zelda and Oracle of Seasons.

The Legend of Zelda
The Digdogger makes its first appearance in The Legend of Zelda. Digdogger is a large sea urchin that shrivels up after a sound attack. To defeat the creature, Link must play the recorder to shrink the creature into a much smaller version of itself. From there, Link can easily defeat Digdogger and reclaim the piece of the Triforce guarded in the Lizard Labyrinth. A larger version appears in the Demon Labyrinth as a mini-boss. In the Second Quest, it guards the Triforce fragment found in the Lizard Labyrinth.

Oracle of Seasons
The Digdogger in Oracle of Seasons is defeated in an entirely different fashion than its predecessor. Using the Magnetic Gloves at north polarity, Link causes the spiked ball that lay in the boss area to smash right into Digdogger. After a few smashes from the spiked ball, the Digdogger will split into its smaller versions. Link must hit each of them with the spiked ball or sword to win the Nurturing Warmth, the fifth Essence of Nature.

Trivia
Vitreous, the boss of Misery Mire in A Link to the Past, is called "Geldogger" (ゲルドーガ, Gerudōga) in Japanese. The suffix -dogger, in addition to its eyeball appearance, connects it to Digdogger. The prefix gel- is probably used due to the fact Vitreous is immersed in a green liquid.