Minecraft wiki entry for The_Wild_Update, associated text: Generates in the deep dark biome only.
Generates in a layer on top of blocks, similar to snow.
Can be placed in all directions, like glow lichen.
Has an animated texture.
Drops nothing when broken without Silk Touch.[4]
Some have parts that are transparent, allowing the player to see the block it is on top of.
May be used in redstone as seen in this video when Mojang Studios talks about the sculk sensors.[7]