Lanmolas

They first apeared in The Legend of Zelda as a powerful enemy appearing only in Skull Labyrinth.

The three Lanmolas guarded the Pendant of Wisdom in the second dungeon of A Link to the Past. They dig out of the floor somewhere in the room, then fly a while and dive back into the sand. When they burrow out from the sand, they make some rubble to fly at Link. After only one is remaining, it will be much faster and it creates more rubble. In this time they can be hit on the head or tail with Ice Rod, Arrows or Sword. However, it's harder to hit them with Arrows and Ice Rod. After they are defeated, Link gets the Pendant of Wisdom and a Heart Container.

Later in Ganon's Tower they guard the way up.

One did appear Link's Awakening as a mini-boss. It has guarded the Angler Key.

Note
This boss is possibly realated to Twinmold from Majora's Mask.