From Minetest Wiki
|Only available in development version!
This article describes a feature in an upcoming release of the game. It has become a part of the development version and will likely become a part of the following stable release. However, things may be subject to change before release.
|A block in Minetest Game|
A firefly is a glowing block that tends to appear in dark areas on the surface area (preferably above Dirt with Grass). It disappears when in light.