A Conspicuous Gravestone
From WoWWiki
A Conspicuous Gravestone can be found in the graveyard at Gadgetzan in Tanaris. [53.9, 29]
Quests
[52] A Grave Situation 
- [52] Linken's Sword
Trivia
To complete the quest A Grave Situation, you must push the stone forward. It's one of the references to the Legend of Zelda, pushing gravestones forward to find hidden items or passageways, in graveyards.
