鉄の殻 [tetsu no kara] or 'iron husk' in Japanese.
Final Fantasy XII
Buy: - (sell: 413 gil)
Use: Golden Helm & Golden Armor & Golden Shield
Drop: Mesmenir, Scythe Mantis
Steal: Leynir, Mesmenir, Scythe Mantis
Poach Leynir, Mesmenir, Scythe Mantis, Sleipnir
Description: Artificers have perfected a technique of extracting and rarefying the mineral content of these hard, iron-rich husks.
Grimoire of the Rift

Buy: - (sell: 60 gil)
Use: Dagriohm, Firewheel Rod, Omnis Cannon
Reward: Sun-ripened Mayhem x3 (repeatable)
Type: Bone, Rank: —
Description: This monster molting is rich in iron and other trace minerals. The moltings are pulverized, then made into various alloys.
Final Fantasy Tactics S

Buy: - (sell: 5 gil)
Use: ?
Obtain: Cend Region/Daravino Wildlands
Description: A common bone
Category: Item