Tenebris

Tenebris is a Hardmode block found naturally generated within the Abyss. After Calamitas has been defeated, it can also convert nearby Planty Mush into more Tenebris blocks. It requires at least a Pickaxe Axe or Drax to mine.

It is used in crafting many aquatic items, typically in conjunction with Depth Cells and Lumenyl.

Trivia

 * In Latin, the word "tenebris" means "dark" or "darkness".