Bone Fragments

Bone Fragments are the remains of slain skeletal undead.

Source
This item drops off any skeletal undead in Western Plaguelands, Eastern Plaguelands, Scholomance, and Stratholme.

As a quest objective

 * Bonescythe Digs Turn in 30 fragments to Rohan the Assassin for 1 Insignia of the Crusade
 * Bone Fragments (quest) Repeatable version of the quest Bonescythe Digs