Crimson Grass Wall

The version growing naturally in the Crimson pushes the biome outward into clean walls beside it, the same way infected blocks creep. A copy you buy and hang yourself does not spread at all, so you can use it as decoration inside a base without seeding an infection you will have to clean up later.

The Dryad only stocks it during a Blood Moon, which is the real gate on buying any quantity. For converting walls already in place, the Clentaminator works but paints a wide radius and takes the blocks and everything else with it. Thrown Blood Water gives far finer control when you only want one patch of wall changed and nothing around it touched. One cosmetic difference worth knowing before you commit: the Corruption version can sprout little flowers and this one never does.