Cosmo's species

Cosmo's species is a species of sapient plant-like aliens in the Sonic X series, to which the character Cosmo belongs. Females closely resemble their plant ancestors, being mostly slender and having an arrangement of petals sprouting from their waists and buds&mdash;or bloomed flowers&mdash;atop their heads. Males are slightly larger than most of the inhabitants of Sonic's world, and are usually rather round, with short tails, small antler-like growths on their heads, and a colored ridge on the top of their heads; they are more similar to trees than flowers.

Members of this species evolve into trees at some point in their lifetimes, perhaps a first stage of death or old age. However, Earthia invented a crystal which prevents going to final phase.

History
For untold years, Cosmo's species was locked in a war against an unknown foe. In an effort to combat them, all the known males joined forces under the command of a renegade scientist named Lucas and willed themselves to undergo unnatural evolution, becoming bestial giant versions of their former selves. However, the evolution process was unstable, and in many cases fatal. Stealing their own world's Planet Egg, they used its power to stabilize the evolution process. Finally, after many died (including Daisy's lover Landar), the planet's leader Earthia, devastated at what they had become, decreed that they would have to leave planet Green Gate to survive and abandoned her world and her mutated comrades to destruction by their enemies.

However, this caused dissension, as the mutated males were unwilling to abandon the fight. They continued to do battle until only five males, including Lucas, remained alive. These five were to become Dark Oak and his henchmen through a finishing phase of their evolution and became the leaders of the Metarex. A mass number of the females however, had escaped into space with Earthia, creating a colony upon which Earthia's last daughter Cosmo was born. Determined to rid the universe of all non-plant life and to have revenge on their former colleagues, the Metarex hunted down and attacked the ship carrying the surviving females, all but exterminating them.

The ship was destroyed, leaving only six known specimens of the race alive: Lucas, reborn as Metarex leader Dark Oak; his commanders Red Pine, Yellow Zelkova, Black Narcissus and Pale Bay Leaf; and Earthia's daughter Cosmo.

Members

 * Cosmo
 * Earthia
 * Galaxina
 * Daisy
 * Landar

Metarex:
 * Dark Oak
 * Red Pine
 * Yellow Zelkova
 * Black Narcissus
 * Pale Bay Leaf

Trivia

 * Females of Cosmo's species resemble the Pokémon Ralts and its evolved forms, Kirlia, Gallade and Gardevoir. They also resemble the creatures from "Maginaryworld", a dreamworld in Sonic Shuffle. For example, Void highly resembles Cosmo.
 * Because they are plant-like creatures, it is possible that the members of Cosmo's species can be reborn. In the English dub, Cosmo lets Tails know of this fact before he had to sacrifice her.