Nether Wart Block compresses nine nether warts into one solid block of saturated, almost lava-coloured red. The texture resembles thick clustered organic growth — somewhere between coral, moss, and dried meat. Unlike most compressed blocks in the game, this one cannot be uncompressed back into the original ingredient: the recipe is one-way, so any wart turned into block form is gone for brewing purposes.

The block also generates naturally as the leaf-equivalent on huge crimson fungi growing in crimson forests. Players who farm crimson fungi for stems and shroomlight automatically accumulate stacks of these blocks as a side product, which is why most builders use them as a free decorative material instead of hand-crafting them. The colour pairs aggressively with crimson planks, magma blocks, and netherrack for hot-themed builds, and it works as a strong contrast accent against grey blackstone or basalt walls. The block has no fire resistance — it can be ignited and will burn just like overgrowth.