Elite Goombule

Elite Goombules are a variation of Goombule fought only once inside Bowser's body in Mario & Luigi: Bowser's Inside Story. Like their weak counterpart, Elite Goombules have an eggyolk shaped body with a yellow core in the center, but they wear Buzzy Beetle shells that deflect jump attacks and counterattacks. To defeat one, the bros. would have to use their newly learned Green Shell attack obtained by collecting all 10 Attack Parts from the Trash Pit. However, unlike their regular counterpart, Elite Goombules are blue.

Trivia
For unknown reasons, the Prima Strategy guide omitted to list this species in the Enemy Compendium.