Slime

A Slime is a naturally spawning mob that was added in Update 0.9.0. They are relatively rare creatures.

Spawn
Slimes spawn in random underground chunks below Y=39 at any light level, and can also spawn in Swamp Biomes at night depending on the phase of the moon. They spawn more frequently during a full moon, and never spawn during a new moon.

Combat
Slimes jump at the player to attack, doing damage depending on their size. Upon dying, they will split into multiple slimes of smaller size, unless already at the smallest possible size, which is smaller than a block. However, the smallest Slimes cannot damage the player.

Trivia
Slime
 * A mistake was made in the spawning mechanics for the Slime and the Ghast, which can't spawn at all. This was fixed in Update 0.13.0.
 * Since Update 0.10.0, Slimes spawn more frequently.
 * Due to their ability to split into small slimes when damaged, all slimes (exception with the smallest sizes) do not die from fall damage, no matter how high they fall.
 * Since Update 0.12.0, Slimes drop Slimeballs and produce Slime particles.