A Spiked Goomba is an enemy from Paper Mario and Paper Mario: The Thousand Year Door. You can't jump on it because it has a spike on its head, and doing so would harm you. You can find it in Rougeport Sewers, Petal Meadows, and Twilight Town. Some of them even live in the dungeon of Rougeport Sewers. Regarding the species Goombario says: "Don't jump on it, unless you have the special spike badge that lets you jump on spiked creatures. Use Mario's hammer to dispatch it, or if the Spiked Goomba is behind another enemy, a Hammer Throw badge."