Slimeball

Overview

Slimeballs make things stick. Their two important recipes are the Sticky Piston — a piston plus one slimeball — which pulls blocks as well as pushing them and is therefore in almost every serious redstone build, and the Slime Block, nine slimeballs, which bounces entities, sticks to adjacent blocks when pushed, and is the basis of every flying machine, elevator and piston door in the game. They also make Leads with string and Magma Cream with blaze powder. Getting them means slimes, which spawn in two places: swamp biomes at night on a full-moon-weighted schedule, and slime chunks below Y 40 regardless of light, which are a fixed 1-in-10 selection of chunks determined by the world seed. Finding a slime chunk and clearing a large flat room in it is the standard farm, and it produces slimeballs indefinitely. Baby slimes can also be trapped and killed with a hopper minecart below. Pandas sneeze slimeballs occasionally too, which is charming and not remotely efficient. Find the chunk, clear the room, and every redstone machine you have ever wanted becomes affordable. One slimeball and 4 string also make 2 leads, which is the cheapest way to move animals across a base.

Making sticky pistons and slime blocks for redstone machines, leads for animals, and magma cream for Fire Resistance potions. Sticky pistons alone justify the farm.

Slimeball is a crafting material item in Minecraft Java Edition 1.21.4. Sixty-four fit in one inventory slot. You get it by killing Panda and Slime.

It is crafted from Slime Block. You will need it for Lead, Magma Cream, and Sticky Piston.

How to get it

Kill slimes, which drop 0 to 2 slimeballs each from the small size. Slimes spawn in swamps at night and in slime chunks — a fixed 1 in 10 of all chunks — below Y 40 at any light level.

Tips

Slime chunks are fixed by the world seed; clear a flat room below Y 40 in one and slimes spawn continuously.
Slime blocks cancel all fall damage when you land on them, which makes them a useful landing pad.
A slime block next to a honey block does not stick to it, which is the trick behind most flying machines.
Swamp slimes only spawn at night and are weighted by the moon phase, so a swamp farm is unreliable.