The Sand Worm is an enemy and boss in Final Fantasy IV: The After Years encountered in the Adamant Isle Grotto. It is the first boss in the game, and is fought against with Ceodore. The Sand Worm is also encountered as a regular enemy in other tales of the game, but is of no threat to those parties.
The player could simply attack, and heal with Potions or White Magic when necessary. A much easier method of defeating this boss simply involves using an Arctic Wind, which should deal well over 500 damage. When its HP gets low, Sand Worm uses Whirlwind to drop Ceodore's HP to 1, and triggers a cutscene. When the cutscene is over, Ceodore "awakens," and his Strength doubles and his HP is restored, and the Sand Worm falls quickly.