Crystalmist

A crystalmist was a hive-like swarm of living crystal creatures that consumed sunlight.

Description
An individual crystalmist closely resembled a big snowflake, about wide. Glowing from within, at its core a point of light that pulsated and slowly changed color over the course of the day. However, their most recognizable form, the one that a swarm adopted when they felt threatened, was a sphere around wide. This sphere shimmered with white light and emitted a deep throbbing sound, one described as ominous. Inert crystalmists during the day resembled salt crystals scattered on the ground and did not glow.

Behavior
Individual crystalmists had no self-awareness of intelligence to speak of—they were estimated to be less intelligent than the typical grasshopper. Nevertheless, they'd evolved the basic instinct to stay close to one another and to form a defensive sphere and even gather into swarms of several hundred specimens, though with no noticeable social organization. In a sphere, their intelligence rose slightly, comparable to a non-insect animal. They were thought to communicate in a basic manner by modulating their colors.

Generally, they simply drifted randomly on the breeze as they absorbed sunlight. During daylight hours, they were inert and immobile; they simply lay on the ground and absorbed light and minerals from the air and rocks around them. They only became active at night.

Combat
When a swarm felt threatened for some reason, individual crystalmists moved into their defensive sphere, comprising about fifty members. While individuals had no means of attack or defense apart from their tiny size, and were easily destroyed, this community was much more potent and capable, but slower. Formation took only a minute. The perceived threat could be as simple as someone trying to walk through the swarm.

If the sphere was damaged, individual crystalmists were destroyed, and losing ten or more of them caused the sphere to break apart into individuals once more. These could not reform for at least five minutes. Having no self-awareness, they continued to reform and attack until the swarm was destroyed or the threat to it was gone.

Abilities
When in a sphere, the individual crystalmists could all release their stored energy at once, producing an intense beam of light capable of burning creatures it struck, up to a distance of, after which it was too diffuse. Sometimes, the beam could reflect off a metallic surface such as a shield or armor, and strike something else in the area. The light was strong enough to ignite flammable materials such as clothing, padded armor, wooden shields, and so on, and explode combustibles like lanterns, thus causing injury and destruction beyond the initial beam. A bright light source in the vicinity, like a continual light, doubled the beam's intensity. The crystalmists could emit a beam approximately once a minute.

Crystalmists were of course immune to mind-altering spells like sleep and charm and to illusions.

Ecology
Crystalmists absorbed light, usually sunlight, to store within and provide energy for their crystalline structures. They also absorbed minerals from the air and ground, including oxygen, hydrogen, silicon, and some forms of carbon. This put them at the bottom of the food chain. They did not prey on any other creature, and other creatures did not as a rule prey on them, though flying creatures like birds and bats occasionally scooped them out of the air in order to balance their diets with additional minerals, and were usually away before the rest became defensive. By and large, animals paid them no attention. Mountain-dwelling, ground-based animals and peoples who recognized them wisely avoided them.

On rare occasions, an individual crystalmist procreated via binary fission, that is, by splitting into two.

Lands
Their typical habit was high temperate and subtropical mountains. Crystalmists were normally found on the world of Oerth, in the Crystalmist Mountains there; local sages debated which was named for which.

However, on Toril, a crystalmist swarm lived in the choraula of the House of the Moon temple to Selûne in Waterdeep circa 1370 DR. They fed on the light provided by the continual light spells there. A very old spell stopped them from both leaving the room and adopting their defense formation. Only a moderately experienced Selûnite priest could make them coalesce and attack others.

Uses
The crystalmists' unique physiology meant they were very valuable in the making of magical items. At the most basic, crystalmists could be used to make dust of illusion and even smoke powder to a high quality. Furthermore, it was theorized that ground crystalmists went into the making of the timeglass of the mage known on Oerth, and that captive crystalmist colonies were trapped inside the unique crystal balls known as the oracles of Greyhawk, and would be there forever because of their mighty magic.