Ebonsand Block

Ebonsand Block is the Corrupted form of normal Sand Block. The only real difference between the two is that Ebonsand can spawn Dark Mummies and Corruption enemies, while normal sand only spawns normal mummies and normal Desert enemies.

At hardmode any corrupted block will turn regular sand blocks that are up to three squares away into Ebonsand.

On top of that Ebonsand (just like Pearlsand) cannot be used to make glass. Something to keep in mind as the Corruption and Hallow slowly eat away at your ocean and desert biomes if you intend to make potions in hardmode. Luckily there is Purification Powder, that converts corrupt blocks back to regular state.