Lumenyl

Lumenyl is a Hardmode crafting material that grows on blocks or is dropped by the enemies in the Abyss after Calamitas has been defeated. It is used in crafting many aquatic items, typically in conjunction with Depth Cells and Tenebris.

Similarly to Crystal Shards, they can also be placed on blocks and walls.

Drop Chance List
The following table displays the chances and quantities that each enemy will drop Lumenyl after Calamitas has been defeated.

Trivia

 * Its name was initially proposed as "Lumenite", and is still referred to as such in the mod's code. It was likely changed in-game to avoid confusion with Luminite.