It is unknown to many players how exactly it got into the game because this wood is the only wood that doesn't grow nor has any logs/planks.
This wood is grey due to the fact that the default brick color on ROBLOX is this exact shade of grey and it hasn't been assigned a wood type.It was first created by an exploiter. He had a hack which allowed him to create blueprints, and the hack also allowed him to use any wood type for the blueprints. The exploiter forgot to put in a wood type one time, and as a result, it created the grey wood blueprint.
There are extremely few blueprints. But due to "Base Dupes", this wood isn't as rare as it is.Sometimes, a glitch may occur in the game when a player tries to complete a blueprint, where the completed percentage will show a percentage number above 100%.
If the player tries to reload their base or move the glitched wall, the wall will be grey. The chance of this happening is very rare.
Due to a recent update, the glitched blueprint will not save if it was created/moved.