A mob in Minecraft. Slimes spawn rarely, and usually only on the deepest levels of a map or at night in swamp biomes (depending on the phase of the moon).
Slimes can spawn in any of three sizes (Big, Small, and Tiny), depending on how much room there is in an area conducive to spawning Slimes. When Big and Small Slimes are killed, they spawn multiple Slimes of the next size down. Tiny Slimes, although they will attack the player, do no damage and are the only hostile mob that can spawn naturally on the Peaceful difficulty setting.