Obsidian Block

The  is a Block in Build A Boat For Treasure. The only chest that rewards this block is the Legendary Chest, but is also purchasable in the shop. This is the second strongest material in the game, behind the Gold Block.

It can be purchased in the shop as a pack of 50 Blocks for 425 Gold.

Trivia

 * On 8/13/19, it was in the Shop.
 * People call this block "Granite" (its actual material in ROBLOX Studio) or "Dark/Black Marble" (as its colors seem to be a flipped version of Marble) the, but it is called "Obsidian" in the game files.
 * Buying Obsidian in the shop is better than getting them from the chest as the Legendary Chest's drops has been nerfed.
 * Since the block is strong, lightweight (requiring only 0.5 balloons to lift a block), and easy to obtain in large quantities, it is one of most commonly used building blocks for builders.
 * This is the second darkest block in the game, the first being the Coal Block.
 * This is the strongest material block that can be obtained from a chest or the shop.