亀の甲羅 [kame no koura] or 'turtle shell' in Japanese.
Final Fantasy III

Buy: - (sell: ? gil)
Drop: Aegir, Balor, Black Flan, Bluck, Cenchos, Dread Knight, Frostfly, Hydra, Kelpie, Killer Hermit, Knocker, Ologhai, Red Cap, Roper, Sea Witch, Sorcerer
Steal: Aegir, Balor, Boss Troll, Cenchos, Frostfly, Hydra, Kelpie, Killer Hermit, Ologhai, Sea Witch, Sorcerer
Treasure: Replito, Lake Dohr, Bahamut's Lair
Type: Consumable
Effect: casts Protect on single target
Final Fantasy V
Buy: - (sell: ? gil)
Drop: many turtle-type enemies
Description: Combine with other Chemist mixing ingredients to produce different effects
Final Fantasy XII
Buy: - (sell: 447 gil)
Use: -
Drop: Adamantitan, Great Tortoise
Steal: Rocktoise
Poach: Adamantitan, Great Tortoise
Description: A tough shell. These are often used to craft crockery, armor, and other items of daily convenience.
Grimoire of the Rift

Buy: - (sell: 60 gil)
Use: Iron Helm, Armguards
Reward: Bonga Bugle - Silversun x2 (repeatable)
Type: Bone, Rank: —
Description: A smooth, curved turtle shell. Skill and diligence are required to preserve its strength during crafting.
Final Fantasy Tactics S

Buy: - (sell: 5 gil)
Use: Boomerang
Obtain: Federation of Nazan/Path of Fangs and Knives
Description: A common bone
Category: Item