Shell

There are several things in the Zelda universe that share a similar name to Shells. Perhaps you are looking for:

Enemies

 * Shell Blade, an aquatic enemy found in Ocarina of Time, Majora's Mask, and Twilight Princess.

Items

 * Mysterious Shells, trading items found in The Legend of Zelda: The Minish Cap.
 * Secret Seashell, power-up items found in The Legend of Zelda: Link's Awakening.