The Chaos Emeralds are a limitless source of a mysterious energy known as Chaos Energy. This energy can be used in many ways, from giving special powers to certain individuals to powering technological devices. Sonic, Tails, Knuckles, Mammoth Mogul, Enerjak and others have used this energy to transform themselves into beings of great power. According to the Isaac the Robot, the original Mobian Chaos Emeralds were formed when the radiation from the Xorda's Gene-Bomb reacted with deposits of the mineral beryl below the surface of Mobius. Because Isaac's data was later discovered to be corrupt, the accuracy of this information has been called into question.

For a long time, the only Chaos Emeralds known to Mobians were the hundreds (perhaps thousands) of Green Chaos Emeralds which existed on Mobius. However, Sonic later encountered Red Chaos Emeralds while he was in space. These had different properties from the Emeralds with which he as familiar. When A.D.A.M. wished to harness all the Chaos Energy in the universe, he summoned all of the emeralds to himself. In addition to the Green and Red Chaos Emeralds, there were five other colors, Blue, Yellow, Gray, Cyan, and Purple Chaos Emeralds. When A.D.A.M. was defeated, these were sealed into the Zone of Silence where their form was changed.

In their new form, there are seven Chaos Emeralds, each in one of the colors of the seven original types. These Emeralds are apparently identical to one another in properties, and are probably slightly different from the original Mobian Chaos Emeralds. The only Chaos Emerald which escaped this reformation was the Master Emerald. The Gray Chaos Emerald is currently in the possession of the Kingdom of Knothole. The other six Chaos Emeralds reside in the Zone of Silence, which has newly been renamed the Special Zone.

Originally, the Floating Island was held up by 12 chaos emeralds. 11 of them were "lost" when Enerjak rose to power and only 1 held up the Floating Island. In Super Sonic vs. Hyper Knuckles special, Knuckles managed to get another chaos emerald from the zone he & Sonic fought in--so 2 chaos emeralds held up the Floating Island. Then, Mammoth Mogul robbed Enerjak of his 11 chaos emeralds and added them to his 1 (Mammoth Mogul has lived so long because he's had a chaos emerald embedded into his chest) giving him 12 chaos emeralds. In Sonic #56, Master Mogul (as he called himself) went for the 2 chaos emeralds that held up the Floating Island to add to his power. However, Locke & Sabre caused a chaotic explosion and as a result the Master Emerald (as it was called) was created with the power of 14 chaos emeralds and Mammoth Mogul's life essense trapped inside. Mammoth Mogul was freed from inside the Master Emerald when Robotnik broke the M.E. into pieces in Sonic #79. Knuckles got back most of the pieces--but not all. Currently, the Master Emerald holds up the Floating Island.

The Roboticizer was originally developed by Sir Charles Hedgehog for medical purposes. It could transform a limb or even an entire body from a thing of flesh into a thing of metal and circuits. When Jules was injured, Sir Charles used the Roboticizer to make him a robot. It worked, but Jules became a zombie who could not talk or think. Charles blamed himself, not knowing that it was Julian (also known as Robotnik) who caused this. Shortly after, Robotnik began using Roboticized Mobians as his slaves. A Roboticized Mobian, or "Robian" normally has no free will of his or her own and is foced to work as a drone for Robotnik. Robians in close proximity to the Ultimate Annihilator were given their free will back, but this was later taken away from all but Jules and his wife, Bernie. A Power Ring can often restore free will, as can the Sword of Acorns. A Robian can only be "deroboticized" with a deroboticizer or the machine that roboticized him or her, and only then if all of his or her parts are the original parts from the roboticization process. In other words, making modifications to ones own robian body will eliminate the possibility of deroboticization. If an Overlander is Roboticized unwillingly, he or she becomes a statue.

All Robians were "derobotized" by Ceneca-9009, except Jules, for medical reasons. It is apparently impossible to to Roboticize mobians.