Mystery Stones are a type of item that can be excavated found in Spectrobes: Beyond the Portals that contain minerals or custom parts. Although the stones vary in appearance, they are all grey with dark grey markings, with at least one question mark on them. Mystery Stones are indicated when scanning on the overworld by a pink marker.
There are many different variates of Mystery Stones within the game, each one holding a different set of items. Unless stated otherwise, they don't hold dark minerals. They include:
- Dinosaur skull: contains two random attack Custom Parts and two random defense Custom Parts for Spectrobes whose fossils can be found on the planet it was found on. They can contain the same custom parts twice. These types of stones cannot be found in areas containing Dark Spectrobes.
- Pie-shape: contains five random C or B rank minerals.
- Piggy bank: contains five pairs of identical random C or B rank minerals.
- Seed pod: contains three random seeds and two random C or B rank minerals.
- Discus: contains 3 Patrol Cruiser part constrution materials and two random C or B rank minerals.
- Treasure chest: contains a pair of identical random high sale price minerals, four C or B rank minerals and another random high sale price mineral.