Chu Worm

Chu Worms are n enemies that appear in The Legend of Zelda: Twilight Princess. They are encountered in both the Lakebed Temple and the Cave of Ordeals. A Chu Worm protects itself in a bubble known as a Shell Jelly, which are invulnerable to Link's sword attacks, although he can break it using an explosive such as a Bomb. Link can also use the Clawshot to drag the Chu Worm out of the bubble. Once the Chu Worm has been dragged out, it begins acting afraid of Link and tries to jump back into its Shell Jelly. If a Chu Worm is outside of its bubble, Link can strike it with his sword a few times to defeat it. Even if the Chu Worm has been defeated but its Shell Jelly is unharmed, it dissolves once the Chu Worm has been defeated.

The first Chu Worm encountered is introduced via a cutscene, unlike most minor enemies, where it sees Link, panics, and jumps into a Shell Jelly.

The "Chu" part of a Chu Worm's name likely refers to Chus, whose gelatinous consistency appears similar to that of Chu Worms' protective bubbles.