MOSS BLOCK

Moss block is the one block in the game that spreads on its own once you have a single piece of it. Bonemeal it against dirt, grass or stone and the moss creeps outward, dragging vines, azalea and moss carpet with it, so buying the first block from the Wandering Trader at 1 emerald for 2 is really buying a starter rather than a supply. One good patch and you never need to trade for it again.

It has no crafting recipe. The game's own files never turn any combination of items into moss block, so short of finding a patch already growing in a lush cave, the trader is the fastest way to get your hands on the first one. It also turns up in 2 of the game's own chest loot tables, so the odd block can land in your inventory without any trading or bonemeal at all.

Unlike the coral he also sells, moss needs no Silk Touch and no water to survive: any tool breaks it back into itself, and it sits fine on dry land. The only thing it asks for is bonemeal if you want it to spread rather than stay a single block.

Only the Wandering Trader, at 1 emerald for 2 blocks, and he will do it 5 times before that slot is spent and gone, since he never restocks. No villager profession lists moss block for sale or purchase at any tier in either edition.

The rate is fixed rather than rolled, so any trader who happens to be carrying it charges the same 1 emerald for 2, and none of them will buy a moss block back off you afterward.

He asks 1 emerald for 2, which works out at well under an emerald each, and 18 of the other 75 come cheaper. Price is the easy part: he draws his stock from a shared pool, so catching one that happens to be carrying moss block is the real constraint.

The Wandering Trader asks 1 emerald for 2 moss blocks. 8 of the 72 villagers that pay emeralds, emptied out:

a dark oak boat against 24 paper for the same 1 emerald, 24 times the carrying, and the shortest wait is the Farmer at 37.5 real seconds of shelf, gathering not counted.

The trader spawns near wherever you are playing rather than in any village, arrives with two leashed llamas, and wanders off again forty minutes to an hour later regardless of what he sold. He carries no workstation, so his five common offers are locked in the instant he generates and nothing you do afterward changes them.

He will not take moss block off your hands. His buying list runs to only 6 kinds of item, and moss is not one of them, so this trade only ever moves emeralds out of your pocket. Because his common offers are a slice of a much longer list, the trader currently near you may not have moss block at all, and there is no reroll: what he spawned with is what he keeps for the whole forty to sixty minutes.

If he does have it, one purchase is usually enough. Name him if you would rather come back for a second slot later, but remember that 2 moss blocks and a stack of bonemeal will cover more ground than buying out his whole 5-use offer ever would.

Buy the minimum and let bonemeal do the rest. One purchase of 2 moss blocks against a patch of dirt, grass or stone, followed by bonemeal, spreads outward on its own and drags moss carpet, vines and the occasional azalea along with it. Buying the full 5-use slot for 5 emeralds is paying for something that multiplies for free.

Two moss blocks make three moss carpet on a crafting grid, which is the cheaper way to get the carpet if the block itself is what you are short on rather than the flooring.

Also on the wandering trader's list: cactus, acacia sapling, oak sapling, birch sapling, spruce sapling and dark oak sapling.

Bone meal on a moss block converts the stone, dirt and gravel around it into more moss, spreading outward in a rough circle. One block bought from a trader can therefore green an entire cave floor without a second purchase.

What it turns into depends on what it lands on, so the same handful of bone meal produces moss carpet, grass and the occasional azalea. Moss also grows in the dark, which is why lush caves are green at light levels where ordinary grass would die.

One moss block gives three moss carpet, and the carpet lays a green skin over a floor without changing the block underneath. That is the tidy way to use moss in a build where spreading would ruin the shape.

Spreading converts stone, dirt, gravel and a few others, and refuses everything else, so a moss garden bounded by planks or bricks stays exactly where you put it.

A composter fed moss gives bone meal back, which means a moss patch and a composter together are a loop that produces the bone meal that grows the moss.

Bone meal on a Moss Block spreads moss across the stone and dirt around it, so the 2 Moss Blocks the wandering trader sells for 1 emerald can seed a whole floor of it. How to Make a Moss Farm in Minecraft (Bone Meal Spread) makes that into a farm.