Minecraft wiki entry for Slime, associated text: In Java Edition, with commands, the size of slimes can be customized. Sizes go from 1 up to 256; the size-256 slime is the largest of any mob in the game, bigger than the ender dragon.
Because a slime's movement speed is tied to its size it becomes impossible for the player to outrun a size 8 slime on flat ground without potion effects.
When a slime searches for nearby targets or checks to see if it should despawn, it checks from a point at the center of its hitbox on the x and z-axis and the bottom of its y-axis. Therefore, a custom-size slime sufficiently huge can be right in front of the player and be completely passive, and it may even despawn if the slime is large enough.
Green-colored Slimes are also present in Minicraft, a 2D Minecraft-inspired game also created by Notch.
If a player walks inside a slime, they can see the slime itself inside of a slime block.
if the player looks at the corner of a glass block, the slime inside the slime block disappears, looking like the slime block is alive.