The Chaos Altar
The Chaos Temple found within level 38 of the Wilderness, west of the Lava Maze, has received a lucrative buff for any adventurer brave enough to travel there.
Players can sacrifice bones on the Chaos Altar inside the temple with a 50% chance for the bone to not be consumed in the process of offering. The base XP gained is the same as a Gilded altar with 2 lit burners.
There is an NPC stood near the altar which will un-note any bones you hand them for a fee. The cost for this is 50gp per bone. This is the only benefit the NPC offers.