Mobs can’t spawn on glass right?
Wrong! Mobs will not naturally spawn on top of a block that is made out of glass.
But they will if it has an opening in the bottom.
This means that mobs can and will still spawn near your home or shelter even if you have made the floors and walls out of blocks created by this material.
This is a blog post about mobs spawning on glass.
Mobs can still spawn near your home or shelter even if the floors and walls are made out of blocks created by this material.
The bottom line: be aware that there could potentially be hordes of zombies, skeletons, creepers, etc.
Coming your way when walking around in an area with glass flooring.
Because they will not naturally spawn on top of it but instead find other ways to get through.