Soul Sand is a brown, sandy block found in the Nether. Unlike most blocks, it is 15/16 of a block tall. It has a second effect: It slows all entities moving across it. This makes it suitable for use in traps, although Cobwebs provide a similar effect as well. However, its final use is much more dramatic: when placed in a T-shape with three Wither Skeleton Skulls on top of the "T", it will summon the Wither.