A Hoohoo Block is an item that is seen in the game Mario & Luigi: Superstar Saga. It is needed so that the Hammerhead Bros. could help make hammers for Mario and Luigi. However, they are only found at the peak of Hoohoo Mountain which Mario and Luigi must climb up. After defeating Dragohoho and freeing Prince Peasley, Hoohoo Blocks head down the river and land in the Hammerhead Bros.' home where they make the hammers for Mario and Luigi.
Despite their name, Hoohoo Blocks are not really cuboid. Hoohoo Blocks are small, round purple rocks that have faces on them.