Slime

The Slime is the fifth hostile mob, added in Minecraft Alpha 1.0.11 and SMP 1.0.17. They appear as green semi-transparent cubes. Slimes come in four official sizes: huge, big, normal, and small. They are the first mob that can spawn in both light and dark areas. These creatures are only naturally found deep underground in the bottom 16 layers of the map. They usually spawn in large, cavernous spaces or open mines. This is partially caused by the fact that a large space is needed for them to spawn. Small slimes apparently spawn in the peaceful difficulty.

Attacking a slime will cause it to break into four smaller sized slimes than of the current one unless a sword is used. Currently, Slimes do not grow larger over time. The small slimes are harmless and can only push the player around.

Slimes of any size will burn instantly upon touching lava and die moments later without splitting into smaller slimes. Slimes cannot swim, therefore they will drown if they are submerged completely in water, as their low jumping height does not get them out of water.

Killing a small slime yields 0-2 units of Slime Balls which currently serve no purpose whatsoever.

There is currently a bug that causes slimes of any size to not be removed when switching to peaceful, unlike other hostile mobs.

Currently, slimes cannot spawn naturally.

Drops
Alpha:
 * 0-2 units of Slime Balls (Only the small ones drop Slime Balls)

Trivia

 * By editing the mob's files, it is possible to make the slimes much bigger, some values creating 50 block high slimes.