千年亀の甲羅 [sennenkame no koura] or 'shell of a thousand-year turtle' in Japanese.
Final Fantasy XII
Buy: - (sell: 1,075 gil)
Use: Demon Shield
Drop: Adamantitan, Emerald Titan, Silicon Tortoise
Steal: Adamantitan, Darksteel, Emeraldtitan, Rocktoise
Poach: Adamantitan, Emerald Titan, Silicon Tortoise
Description: A slightly worn shell. Considered antiques, the value of these pieces varies with the pattern of the cracks and pit-marks on the surface.
Grimoire of the Rift

Buy: - (sell: 400 gil)
Use: War Trumpet, Yoichi Bow, Brevis, Genji Gloves
Reward: An Earnest Quandary x4 (once), Wanted: Shiny Maces (once)
Type: Bone, Rank: ★
Description: This nicely weathered shell has great value among curio aficionados.
Final Fantasy Tactics S

Buy: - (sell: 50 gil)
Use: Grand Cannon, Shield Ring
Obtain: Federation of Nazan/Path of Fangs and Knives
Description: A somewhat uncommon bone
Category: Item