The Spike Top Shell is a new power-up first appearing in Super Mario Crossover Mission. The user can climb walls and walk across ceilings, and cannot be damaged from above when crouching. He/she is also immune to fire enemies such as Fire Bros., Podoboos, and Fire Snakes.
Spike Top shell also appear as objects in Mario games. In Paper Mario games Spike Tops have an attack where they go into their shell and speed right into Mario. Also in some Mario games if I Spike Top is hit into will retreat into into its shell like Koopa Troopas and Buzzy Beetles.