Firefly swarm (new transparent light emitting block)

The firefly swarm is a transparent block that emits a light level of 14. It is simply made of very small light particles (fireflies).

It cannot be crafted, but it can be "mined" using a net, crafted with strings and sticks.

The firefly swarm "spawns" (like a mob) in dark forests when light level is lower than 3, replacing an air block, but can only spawn within 3 blocks of a grassblock, leaves or dark oak wood.

I really think this would be great for "natural" illumination of gardens and such.