After his daughter left the dimension, Mephiles decided to recreate the world in his image, transforming it into "a crystalline paradise". Upon completing this goal, he felt as if he had missed something. Tossing a Chaos Emerald in his hand, he pondered his problem until he realized the solution was right in front of him. Traveling to the northern pole, Mephiles arranged the emeralds in a circle, and used their power to turn them into towers that extended beyond the atmosphere. He then made an onyx tower within the circle, and proceeded to move to his next project...
Like all obelisks, the Crystalline Obelisks are shaped like long rectangular prisms with four-sided pyramids at their tops. Each one has the color of the Chaos Emerald it once was.
The obelisks have the same powers as the Chaos Emeralds, with the only restriction being that they're stationary. Mephiles mainly uses them to warp between dimensions via Chaos Control. Interestingly, they can be fragmented, and they will regenerate in seconds. The fragments, dubbed Obelisk Shards, have the same powers as the obelisks, and can crystallize any object; however, they can only be used once before disintegrating into nothing.