Corrosive dwarf Bipes or Hive Pebbles
These cave dwelling bipeds subsist off of iron potassium and sulfur found in rocks. This digestion occurs with the help of an internal lithotropic microbial ecosystem mostly featuring endoliths.
With the help of their protective structures these creatures are extremely resilient to high pressures, high temperatures, and high amounts of radiation. Their bodies protect the internal rock digesting bacteria from otherwise unsurvivable subterranean environments.
Each eye has 2 bioluminescent pupils. Eyesight is poor and the light is primarily to warn potential predators to stay away. Each foot has 3 bulbous toes designed for maximum traction on nearly flat surfaces.
A mildly toxic solution that quickly solidifies is a by product of digesting most rock. A long tongue spreads this solution to produce a hollow translucent purple structure on the creature's back. This structure grows until it is larger than the creature itself. the creature then lives inside it similar to a hermit crab.
These solidified adults huddle together in huge swarms to eat nutrient rich rock. In times of space food, swarms distribute food among st themselves. The hard work of scrapping the toxic shell against a wall to dissolve tougher rock is also distributed. To accomplish this, swarms constantly re arrange themselves much like penguins distributing warmth.