http://www.wowhead.com/item=5075#comments
This is the dialogue that is offered to the player when you speak to Bael'dun Excavator near the collapsed cavern in the excavation site. Speculation is that it is referring to an Old God... As you have been able to since Vanilla, and still are able to find, blood shards - which are supposedly solidified blood of an Old God, equivalent to Yogg Saron's Saronite.Turn away, <class>.
Before the cataclysm hit, we found something.
We dug something up that should've stayed buried.
Pray to whatever you believe in that the landslide was enough to keep it down...
What do you think it refers to? Is there credence in the Old God speculation, or is it something else?