Not sure if you're falmilar with Unreal lore, but the crystal and cave ref you pulled would be right at home in it. http://liandri.beyondunreal.com/Tarydium is pretty much in every unreal game in some form either crystallized blue shards or something else referenced :D Sweet ref pics! The glow worms cave and the moss…
The ruins of a lost civilization found underground. Where glowing crystals were were centered around their culture. Everything was either hand carved by the tribe's hands or water. The reason for the people's death is unknown, and their tribe was forgotten for years until one day it was rediscovered.