Massively has learned about many areas of Lord of the Rings Online: Moria of Moria throughout Turbine's Hero's Guide series, yet none could be as structurally important (literally) as the Foundations of Stone. Being the bottom-most level of the mines, this area is actually the foundation of Khazad-dûm. In fact, the murky lake in the center of this level holds a remnant from the Bridge of Khazad-dûm which had fallen from Nud-melek above.
Being in such a remote and subterranean locale, the Foundations of Stone is home to a great infestation of fungus that deforms the creatures who dwell near it. You'll see Orcs, Trolls and other creatures plagued by the mysterious fungi, hoping to spread a bit your way.