Deep beneath the surface, darkness reigns. Most living things that inhabit the depths adapt to the eternal night of underground living. For those that don't, Luma provides an alternative to the darkness.
Luma is a fungus that forms vine-like colonies near deposits of sulfur-bearing minerals that provide their primary source of nutrients. The vines support support an array of pendulous globes that consume the sulfur compounds, producing both heat and light as part of the reaction. A single Luma colony can extend hundreds of yards through natural caverns and caves, creating pockets of light and warmth in the darkness.
Luma colonies attract a variety of underground life. The light and warmth they provide is sufficient to support primitive plant-life such as algaes and mosses. These plants, in turn, provide the basis for a broad food chain. Intelligent under-dwellers have learned to cultivate Luma, using it as a basis for their own societies and cultures.
The typical Luma colony spans 200 yards of caves and caverns. Dozens of vine-like tendrils rise from the tangle of tiny roots that mark the base of the colony. The tendrils spread and climb across any surface, sprouting tiny roots of their own, questing for additional sources of nutrition. Fist-sized globules sprout at uneven intervals, each emitting pale yellow light, equivalent to dim sunlight, in a 60 foot radius. The ambient temperature within the area containing the colony is elevated 10 to 15 degrees about the surrounding area.
A colony that exhausts its food supply will wither and die, each pod spraying forth a cloud of dust-like spores that cling to anything they touch. Spores that find a fresh sulfur deposit, sprout and form a new colony in two to four days.