A Super Mario Mystery Block!
A ? Block (alternatively Question Mark Block), also called a Question Block, a Mystery Block, a Prize Block, a brown Question Mark Box, or simply a ?, is a type of block found in midair, often containing coins, Super Mushrooms, or Fire Flowers, and may also be invisible
Source: https://www.mariowiki.com/%3F_Block
Included formats in download: .blend / .dae / .obj / .stl / .fbx / .gltf