Barrier

Barriers are blocks that are invisible and can be placed. When holding the tile in hand, all barrier blocks become visible to the user. It can be destroyed by explosives.

Trivia

 * This item may be inspired by Minecraft's own |Barrier Block.
 * It can't be obtained through normal means, is invisible unless its own block is held, is indestructible, and can only be broken in Creative Mode, a special player state that allows access to nearly every block, flight, and invulnerability.
 * It is not a direct copy, since these tiles are destructible.