Ash Block

The Ash Block is a block that covers the upper section of The Underworld, and the lower 'ground' layer in which Hellstone is encased. Used for building and growing Fireblossom.

Trivia

 * This block is made of ash, a residue left behind when something is burnt.
 * The block is also likely a reference to the character Ash Ketchum, the protagonist of the internationally acclaimed Pokémon franchise.