The Cobalt Star is the name given to the power source for Professor E. Gadd's time machine in the game Mario & Luigi: Partners in Time. The Cobalt Star was shattered into multiple Cobalt Shards by Princess Peach after she used it to trap Elder Princess Shroob, the leader of the Shroobs that were invading the Mushroom Kingdom of the past. Destroying the star also caused Time Holes to appear between the past and present, and with the help of their infant selves, Mario and Luigi go about retrieving the shards and reassembling the Cobalt Star to fix the fabric of time and save Peach from the aliens. Baby Luigi and Kylie Koopa both realize something is amiss with the Cobalt Star, but the full truth is not revealed until it is too late: all of the Shards are assembled and Elder Princess Shroob uses her regained power to break free of her prison and attack the heroes.
It appears that the Cobalt Shard does not exist anymore in the Mario universe, as Elder Princess Shroob states that the star "is no more". Interestingly, the Shroob monarch can create time holes during the final battle, suggesting that she absorbed the Cobalt Star's powers to enhance her own.
Cobalt Shard Locations
Below is a list of where the six Cobalt Shards of the Cobalt Star are located.
Names in Other Languages