Soul Sand

Slow sand (aka "mud", "hell mud" or "soul sand") is a brown-grey dirt-type block, found in The Nether.

Properties

This material has the similar to Dirt but has several unique features:
 * Grass cannot grow on it.
 * It can slow the movement of any player or NPC.
 * Players sink slightly into the block while walking on it.
 * It is not flammable.
 * Sneaking on a slow sand block will not prevent you from falling from the block. (Bug?)

Uses

There are currently no recipes involving slow sand. It is an effective building material when creating a dock, because boats are not destroyed when colliding with a slow sand block at high speeds.

Trivia

 * The texture resembles a collage of faces. These faces are said to look like those of Creepers.
 * This block stopped generating in the v1.2.0_01 update; in its place, gravel was generated. This was fixed in the v1.2.0_02 update.
 * The first appearance of this block was on Notch's blog.