The Geode is a giant, black, dome-shaped rock containing a synthetic storm within. The Geode lies at the bottom of an enormous crater and has a small crack currently held together by a piece of duct tape. Garnet implied that there was almost an explosion at the location. It first appeared in "House Guest"; its latest appearance was in "Warp Tour". It is currently unknown whether it is a corrupted Gem or an ancient Gem weapon.
The Geode was cracked by unknown means, thus Steven and the Crystal Gems rushed to repair it to prevent the storm from escaping, and in turn, vaporizing everything. When they arrived, lightning was spitting from the cracked Geode and creating a thunderstorm overhead. Garnet hoped Steven could seal the crack with his healing powers of saliva, but his attempts had no effect.
Steven and the Gems returned to the Beach House to devise a new plan. Meanwhile, Greg wanted to make amends for lying to Steven, so he traveled via the Warp Pad to fix the Geode himself. Steven chased after his father, and together they used a roll of duct tape from Greg's toolbox to temporarily seal the Geode.
The Geode was revisited as the Gems traveled, searching for the Flask Robonoids that Steven witnessed. It was revealed that the duct tape from "House Guest" is still holding in the storm.
- The Geode bears an uncanny resemblance to the slow explosion in Akira.
- A geode is a rock containing a cavity lined with crystals or other mineral matter. Because of this, it is theorized that the Geode contains a large mass of Gems.