Raurg bones are associated with the Prayer skill, giving 96 prayer experience when buried.
They are obtained from Zogre coffins, which will often break lockpicks and decrease players' thieving abilities upon opening using thieving methods. They can also be obtained by looting a zombie impling jar. (Zombie impling require level 87 hunter to catch.) These bones are impractical to train prayer with, as they are significantly more expensive than Frost dragon bones, therefore it is recommended to sell raurg, fayrg, and ourg bones accumulated from ogre coffins.
This table can be used to compare and decide on how to train with the bones for the most desired cost versus experience gained. Notice how the cost in coins per XP point varies greatly depending on how the bones are used — but also remember that the different methods have different training speeds.
The price of raurg bones significantly increased on 19 September2012, due to the release of the challenge system.
Training from level 1 to level 99 Prayer by only burying raurg bones would cost 6,291,859,840 coins, assuming no experience boosts are used. Training to a total of 200m experience would cost 96,541,697,560 coins. This method is currently the worst method in the entire game of training a skill cost-wise.