Bone

Bone (BO) is a reagent which features in the Pagan magical tradition of Necromancy.

Sosaria and Britannia
Bone seems to figure occasionally in Britannian ritual magic, and many ceremonial rites require the use of bones deriving from a particular animal, such as a dragon or harpy. Outside of a few isolated cases, however, bones figure little in general Britannian spellcraft.

Serpent Isle
Bones are not used in any known magical traditions on Serpent Isle, but they appear to have held some ritual significance to the goblin tribes of region, who frequently manufactured ornaments, jewelry and fetishes from the bones of slain enemies.

Pagan
In necromantic magic, bone serves to represent the force of will and is used in the crafting of spells which involve communion with the dead. It is one of the more easily obtained reagents used in Necromancy, as the followers of Lithos are accustomed to frequent the Catacombs which house Pagan's departed.

Ultima Online
In the Stygian Abyss expansion for Ultima Online, the Gargish magical school of Mysticism makes use of bone as a reagent.