Nubbin

A Nubbin is a pimple like thing that is found throughout Bowser's body. In order for it to work, Mario must hammer this object in order to make something good happen, like opening blocked areas, fire cannons, make platforms appear, etc. They seem to be mostly red to match the tone of the flesh inside of Bowser, but sometimes have a different color (for example: purple) will appear, with can cause a different effect from the regular Nubbins (like powering up Bowser).