Deep Ones

Far below the surface of Hermes, deeper than all but the oldest mines reach, live the Deep Ones. A race of multi-armed and semi-advanced beings that guard those dark depths with everything they can. Their skin is black as coal, though white markings cross and swirl all across the body, as well as two pairs of white eyes, give them a ghostly appearance in the dark.
In their deep caverns and crevices, they congregate around what seem to be old-world power structures. Similar to a nuclear generator, but no one has ever gotten close enough to one to actually observe their function or purpose. Despite this apparent advantage, they use Victorian-era weapons (single shot, high caliber rifles), survive off of small rodent-like creatures and mushrooms, and live huts constructed from a sort of mud.
Whatever it is that they live around, it certainly isn't a teacher.
Their language is a series of insect-like chattering and clicks, making communication between species difficult if it's possible at all. However, there are many reported cases of the Deep Ones coming to know human settlers, all independent, and even coming to their aid. The reasoning for these seemingly random bondings is unknown.