Mud Block

A Mud Block is a Dirt-like Block that can be found Underground and crafted near Water while having a Dirt Block in the inventory. Mushroom Grass Seeds and Jungle Grass Seeds can only grow on mud.

When placing a Jungle Grass Seed on a Mud Block at below a certain depth (60 feet in small worlds, 120 feet on large worlds), you can create an Underground Jungle. Mushroom Grass Seeds can also grow at above 0ft.

At hardmode any corrupted block will turn regular mud blocks that are up to three squares away into dirt. If there was jungle grass then it also will be converted to corrupt grass. This does not affect mushroom grass tiles. Even so, mud is converted very slowly and the resulting dirt cannot be converted further if grass cannot grow on it, making it a possible buffer to buy time against the encroaching corruption. To offset this, Mud Blocks can be crafted from Dirt Blocks, allowing players to create a new supply. Mud hit by blue, purple or red solutions sprayed by the clentaminator will be converted into dirt, and any grass that occupies it will be converted into that of the sprayed biome. Similarly, mud hit by the biome water bottles will be converted to dirt and the grass will become that of the new biome.

History
Schlammblock Bloc de Boue 진흙 블록