"A giant-sized Goomba, as the name suggests. In Super Mario 64, punching and kicking had no effect on this brute. It could be stopped like normal Goombas--by jumping on it from above. A colossal Goomba appears as the boss of world four in New Super Mario Bros., but that's a Mega Goomba, not a Giant Goomba."
These giant-sized Goombas make quite an impression. Some will net you a coin when you jump on them, and others will split up into smaller Goombas. They're often much stronger than normal Goombas, but jumping on them a few times usually does the trick. There's also an even bigger one out there: the Megasparkle Goomba. So shiny!