Also known as Calline Prime, this is an alterash prime variation of the original crystalline biome, caused by what’s called a  crystalline primification.
 crystalline primification.
These crystallic caves are dimly lit via soft green light emitted from the crystals that grow here. Some of those crystals are edible, by the way.
ct_crystalline_prime/biomes/alterash_prime/esetera entrance/ct_crystalline_prime.biome