Junior Shrooboid

The Junior Shrooboid is a small green monstrous Shroob who appeared in Mario & Luigi: Partners in Time. During the events of the game, this strange creature used Professor E. Gadd's time machine to travel from the past to the present. Eventually, Junior Shrooboid winds up in Princess Peach's throne room. Mario immediately confronts the alien (while Luigi runs away scared). The Junior Shrooboid is the first enemy to be fought by the adult Mario.

In battle, the Junior Shrooboid attacks by spinning into Mario. Mario can Jump over this attack and stomp on the Junior Shrooboid in the process.

After the battle, Professor E. Gadd places the Junior Shrooboid in a fluid tube, keeping the alien alive for study. E. Gadd discovers that the Junior Shrooboid reacts strongly while in the presence of the Cobalt Star shards. The professor hypothesizes that the Cobalt Star could be used to destroy the Shroobs, and commands Mario and Luigi to recover the remaining star shards. Unfortunately for the heroes, the Junior Shrooboid reacted so strongly not because the Cobalt Star could defeat the Shroobs, but because the Junior Shrooboid knew that its leader was imprisoned inside the artifact itself.

Trivia

 * In Mario & Luigi: Bowser's Inside Story, while Mario and Luigi battle the Shroobs, eight Junior Shrooboids can be seen frozen in blocks of ice. Outside of the battle, one Junior Shrooboid is the only frozen Shroob that can be seen, although two other ice blocks with unknown Shroobs are present. In the Nintendo 3DS remake, however, there is only one Junior Shrooboid.
 * Junior Shrooboid is one of the two only bosses fought in the present Mushroom Kingdom (the other being Shrowser).
 * Junior Shrooboid's color, age, and relationship with the Elder Shrooboid parallel those of Luigi and his relationship to Mario.

Junior-Shrooboid Shrooboide Jr.