Obsidian aka black marble or Granite is a block in Build a Boat for Treasure. It is usually obtained with high-tier chests, such as the Epic Chest (Rare), and the Legendary Chest. This is the second strongest block in the game (behind the Gold Block), and among one of the rarest items in the game.
- People call this block "Granite", but it is called "Obsidian" in the game files.
- It uses the ROBLOX Granite texture.