Crystal Feeders

Inside the Bazdresra Sniarsti is a large system of caves and other underground networks that have been used for centuries to mine materials in both Eoion and Yzel. One of those materials is called Irum, a substance used to house essences. 
A major danger for those who mine irum is the crystal feeders. These creatures live deep inside the mountains, far from sunlight and plants, with very little in terms of water and other food sources. Most cave dwelling creatures come out in order to feed and then return to the caves for safety. However, the crystal feeders can survive for their entire life cycle within the caves. 
Their danger is not because they are predatory, but due to their territorial nature. Each one is approximately the size of a small cat, about 0.5-0.6m in length. They are entirely hairless, with blind, vestigial eyes, and pale skin. Their tails are prehensile for grasping onto the outcroppings of rock that line the saves. Unlike any other creature on the continent, the crystal feeders have developed the unique ability to sense light not through their eyes, but through sound. They can hear the slight vibrations of light essence magic and use this to locate their food source. 
Near irum deposits, the essence magic that gathers there infuses other rocks, causing them to faintly glow. This has helped humans locate the irum they desire. For the crystal feeders, this is their food source. They take in the light given off from the crystals and, when finished, will consume the rock itself or take it back to their nest. Humans who come near the creatures can expect to be attacked as the crystal feeders believe they are competition for food. 
Some miners have developed the ability to use the creatures as a way to find irum, but this is dangerous and requires extensive knowledge of the crystal feeders and the cave systems.