What are the brown musroom things in Mario Bros?

The brown mushroom-like creatures in Mario Bros are called "Mushroom Platforms" or "Mushroom Blocks." They serve as interactive elements in the game, often providing power-ups or items when hit from below. Additionally, the brown mushrooms can refer to "Mushrooms" in general, which grant Mario special abilities, like growing larger or gaining extra lives. These elements contribute to the gameplay mechanics and exploration in the Mario universe.