The original concept for the ultimate life form was a creature who would open the doors for a better world. That is until Prof. Gerald Robotnik went insane with rage, and created the true ultimate life-form, Codename: Shadow, to bring fear and destruction to the people of Earth.

Finally freed from the military base 50 years later by the one, the only, Dr. Eggman (grandson of Gerald), Shadow wasted no time in carrying out the wishes of his creator, and had all of the Chaos Emeralds brought aboard the Space Colonly ARK to power the Eclipse Cannon, which he promised the mad doctor he could use to take over the world.

One very important ability given to this hedgehog is Chaos Control. By using this method, allowing him to warp time and space and instantly transport from one place to another, is what truely makes him the ultimate lifeform. That is, until he learned that another hedgehog had mastered the trick, and had equaled him in power. With the power of the seven Chaos Emeralds, Shadow becomes Super Shadow. Super Shadow is invincible, and just as strong as Super Sonic.

Though Shadow is a wee bit wound up in himself with being the "ultimate lifeform" and all, he does have and ooey gooey caramel center inside. Shadow has memories of a mysterious girl named "Maria". The young, crippled girl was one of his only friends aboard the space colony ARK. Before being sent to Earth, he made a promise to her: to make every human on Earth happy. Shadow lived up to this promise by helping to defeat Biolizard (prototype of the ultimate lifeform) aboard the ARK and preventing the space colony from colliding with the Earth by using Chaos Control to transport it back into orbit around the planet. In doing so, Shadow sacrificed his own life, not only to keep his promise, but to truly realize the meaning of his own existance.

Sid and Tone were locals of the Rocky Valley Zone who stumbled across a cave, complete with it’s own buried treasure hidden at the bottom of the cave. Dreaming of fortune they decided to be weary and sell the gold piece by piece, dressing up as Aliens to scare away any tourists in the area whilst they sold the gold piece by piece to stop anyone getting suspicious. Everything was going fine until Amy and Tekno turned up, and after seeing the aliens dug through to the cave behind them and found out that the UFO was made from Paper Mache! Sid and Tone removed their disguise and revealed their plan, after which Amy laughed them out of the cave by convincing them that it was Geeks Gold, a prop used in a local film called “Caves of Gold.” Blaming each other for the mistake they accidentally shot the roof of the cave, burying the entrance and angrily they departed. They never found out that there never was a film called Caves of Gold, and never saw Amy and Tekno digging to get back into the cave behind their backs.

Silver Sonic was first used to guard the Death Egg from Sonic. It probably goes without saying that he failed miserably. Silver Sonic was then rebuilt in a much more tall and imposing mech, and used to guard the Sky Sanctuary Zone while the Death Egg was being relaunched from Angel Island. He was reactivated AGAIN afterwards to make one final attempt to steal the Master Emerald. And he put up quite a fight to keep it by actually absorbing its power to become Super Silver Sonic. But it just wasn't enough to defeat Knuckles, and the remains of Silver Sonic went down with the Sky Sanctuary Zone.

Appearantly, Silver Sonic was rebuilt again, and was placed within an energy tube in the Final Egg. Unless you count the exploit in Sonic Pocket Adventure, that's probably where he is to stay...