BUBBLE CORAL BLOCK

Bubble coral sits at the purple end of the trader's five colours, closer to amethyst and purpur than to anything else in his stock, which makes it the one coral block that actually matches a build already leaning on those materials. On its own, away from purple accents, it reads as an odd note in an otherwise blue-green reef palette. The Wandering Trader sells the live block for 3 emeralds.

It shares the same two doors in as every coral colour on this site: no recipe exists for it in the game's own files, and a pickaxe without Silk Touch enchanted on it walks away from a live block with nothing. The trader is the route that skips the reef and the enchantment both.

Whether it is worth the 3 emeralds comes down to what else is in the build. Next to amethyst geodes, purpur pillars or a bed of purple wool it earns its place; dropped into a generic reef tank alongside brain and tube coral it mostly just adds one more hue to a display that already had plenty.

The Wandering Trader alone, at 3 emeralds flat, 8 times before the offer is spent for good. He never restocks a used slot, and no villager profession lists bubble coral block on either side of a trade, buying or selling, at any tier.

Because the trade file holds one fixed number rather than a range, the price does not drift between traders. Whichever one you find carrying it, it costs 3 emeralds.

He asks 3 emeralds each, and 53 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 bubble coral block is the real constraint.

The Wandering Trader asks 3 emeralds for a bubble coral block. 8 of the 72 villagers that pay emeralds, emptied out:

3 jungle boats against 96 sticks for the same 3 emeralds, 32 times the carrying, and the shortest wait is the Butcher at 1.9 real minutes of shelf, gathering not counted.

The trader is untethered from any village and has no workstation. He spawns wherever you are in the world, two leashed llamas behind him, and leaves again forty minutes to an hour later no matter what you bought. His stock, including whether bubble coral block is on his shelf at all, is fixed the second he generates.

You cannot sell it back to him. His buying list covers 6 kinds of item, none of them coral, so bubble coral block only moves one direction across the trade window. And since his five common offers are a slice of a much larger table, the trader in front of you might just not have this one, with no reroll to fall back on if he does not.

A name tag is the only real workaround. It removes his despawn timer, so a merchant who does happen to be carrying bubble coral block stays put and keeps the offer open until you have used all 8 of the slot.

Buy it to match, not to fill. Bubble coral's purple pulls a build's eye toward whatever else is purple in it, amethyst, purpur, magenta concrete, so it earns more attention as a pairing than as a stand-alone reef block. A full 8-use slot runs 24 emeralds, worth it if that purple has somewhere to sit next to.

It still fades without water. A bubble coral block that stops touching a source block bleaches out to the same pale grey as the other four, so keep the pool, tank or ocean floor underneath it before you spend the emeralds.

Also on the wandering trader's list: fire coral block, horn coral block, tube coral block, pale hanging moss, sulfur spike and rooted dirt.

Bubble coral is the purple member of the family, and like the rest of them it is only purple while it is wet. Dry it out and it becomes the same grey dead coral every other colour becomes, which makes the five living colours effectively one block with a paint job that can be lost.

Getting one out of a reef intact takes Silk Touch; anything else hands you the dead version. Coral reefs also only generate in warm ocean, so a world without one nearby has no coral at all unless somebody brings it.

Indoors, the practical build is a sealed water column behind glass, or waterlogged stairs and slabs around the block. Both keep the colour without a visible pool.