Stone Guardians are level 60 and 61 elites in Un'Goro Crater.
They roughly patrol the river that flows from the southeast to the northwest of the Crater.
They are the only mobs that drop the used in some crafting professions. The Guardians are flagged as non hostile and will not attack unless attacked. They are reasonably easy to kill as a well-geared level 60 because they move rather slowly, unlike the sDevilsaurs that also inhabit the region.