Transforming Stones (Japanese: へんしんの石) are round, shining stones in The Legendary Starfy. They are made of natural energy that allow the Bunnerans to transform. They have a picture of Bunston's relevant power inside them. There are eight Transforming Stones available in total, that allow Starfy to combine with Bunston and transform into either Monstar, Starpedo, Roostar or Starfright. The other four Transforming Stones are upgrades to the aforementioned forms that give enhanced abilities. The upgraded Transforming Stones shine brighter to the initial Transforming Stones but otherwise look the same.
In Area 2 of Planet Bunnera, 'Modo's Cosmic Express' - it is revealed that Modo was the original owner of the initial Monstar transforming stone but he gave it away. Bunston then gave it to Starfy. Much earlier in the game, in Area 3 of Gluglug Lagoon, Starfy jumps into Big Squiddy's left large tentacle to save Bunston, and Starfy is transformed into Monstar. It is assumable that Starfy and Bunston used the energy of the Monstar Transforming Stone to undergo transformation, but this is not explicit.
The rest of the Transforming Stones are found by Starfy. If the player uses Moe's Sniffer near a Transforming Stone (other than Bugawk for unknown reasons) Moe's eyes will glitter with golden balls to indicate that a Transforming Stone is nearby.
When Starfy obtains a Transforming Stone, a short tune of the same name plays.
After a Transforming Stone has been acquired, Starfy can morph with Bunston by entering a thought bubble with the relevant power inside, although when Starfy first transforms into Monstar, he simply jumps into Big Squiddy's left tentacle with Bunston to transform.
- The Bunnerans can undergo other transformations including butterfly and elephant forms, seen during the Mashtooth's Master Plan and Starfy's Ending Story cartoons. It is possible that they may have used certain Transforming Stones unavailable to Starfy and Bunston.
- The attack names (i.e [Super] Spicy Belly and the like) are simply the transformations names in Japanese, with the upgrades adding “Super” to them, like in English.