Shaikahan bones

Shaikahan bones are associated with the Prayer skill. You get them when you kill a Shaikahan, which can only be killed with karambwan poisoned (kp) spear. Shaikahan bones give 25 Prayer experience when buried. You can cast alchemy on these bones, but both high and low will give you 0 coins. They give 100 prayer experience when used with the ectofuntus.

Legend has it that when Zamorak and Saradomin fought in what is now known as the wilderness, their fallen soldiers turned into the Shaikahan and the final spell that destroyed the wilderness gave them the quaility that lets them only be killed with karambwan poisoned spears.