Thwomp

Thwomps
Thwomp is a large stone block that is usually covered in spikes. They are either Blue or Gray and have an angry face. They first appeared in Super Mario Bros 3 and tried to squish Mario whenever he walked underneath them. They have also been in Super Mario World, Super Mario Kart, Super Mario RPG, Super Mario 64, Mario Kart 64, Mario Party, Mario Kart: Double Dash!! and Mario Kart DS.

Variations
Thwimps: Small versions of Thwomps found only in Super Mario World. They jump from side to side.