When the team discovers that Cosmo's brain is emitting a signal to the Metarex, they plan on trying to eliminate the signal, except that the signal is connected to the part of her brain that translates sounds and sight. While Tails and Cosmo are torn about this, Knuckles pushes for the surgery. Meanwhile, Amy starts searching for Sonic (as always), but ends up bumping into Rouge. They both discover that this planet is not only Cosmo's homeworld, but the Metarex's as well. They also discover that Cosmo's people were able to transform into huge dinosaur-like beings to protect their planet from an alien invasion. However, a few of them wanted to be able to completely destroy the alien hoarde, and so crystallized the Planet Egg in order to keep the transformation from sapping their energy. They eventually led to the abandonment of the planet. Cosmo, horrified by the fact that the Metarex are using her to spy on them, intends to leave, but Tails reassures her that they all will help her defeat the Metarex. Sonic and the rest of the gang also support the new resolution, and they all are ready for an attack on the Metarex, maybe the last attack. At the end of the episode, Bokkun arrives, telling Shadow and Chris that Eggman has been captured by the Metarex. (thetvdb.com)