Sinnoh Underground: Every Fossil, Stone & Item You Can Dig Up
Every fossil, evolution stone and item you can dig up in the Sinnoh Underground — and the trainer-ID split that decides Cranidos or Shieldon for you.
The Underground is the one part of Sinnoh with no wild Pokémon in it at all — and it still decides which Pokémon you can own. Every fossil in Diamond, Pearl and Platinum is dug out of its walls, six of the region’s evolution stones come out of the same walls, and one of the two Sinnoh fossil Pokémon is locked away from your save file before you make a single choice. This guide is the complete list of what is down there, read out of the games’ own data.
- Game
- Diamond Pearl Platinum
- You need
- The Explorer Kit, from the man in Eterna City — after that you can dig down from any outdoor spot in Sinnoh
- Pokémon it gives
- 7 fossil species, revived at Oreburgh City’s Mining Museum at level 20
- The catch
- Your trainer ID decides whether you get Cranidos or Shieldon — never both
The fossils, and the choice the game makes for you
Fossils come out of the digging minigame and are revived at the Mining Museum in Oreburgh City. All seven arrive at level 20. Two of them are gated on something you never chose and cannot change: the last digit of your trainer ID.
| Fossil | Revives into | When you can dig it |
|---|---|---|
| Skull Fossil | Cranidos | Odd trainer ID only — from the start |
| Armor Fossil | Shieldon | Even trainer ID only — from the start |
| Helix Fossil | Omanyte | After the National Pokédex |
| Dome Fossil | Kabuto | After the National Pokédex |
| Old Amber | Aerodactyl | After the National Pokédex |
| Root Fossil | Lileep | After the National Pokédex |
| Claw Fossil | Anorith | After the National Pokédex |
The five Kanto and Hoenn fossils are not merely rarer before the National Pokédex — they are not in the table at all until you have it. Afterwards they become the common ones: together they are about three times as likely to turn up as the Sinnoh fossil your trainer ID allows. If you want a second Rampardos or Bastiodon, that scarcity never lifts.
Your trainer ID splits those five as well, though never all the way to zero. On an odd save the Helix Fossil and Claw Fossil are the easy ones and the Dome Fossil is the rarest fossil in the ground; on an even save it is the other way round, with the Dome Fossil and Root Fossil common instead. Old Amber is the one fossil your ID does not touch.
Evolution stones — the reason to keep digging
Evolution stones are scarce in Sinnoh, and the Underground is the one place that keeps producing them. Every stone below evolves at least one Pokémon in these games — and only these evolutions, which is worth saying because later generations added more. In Diamond, Pearl and Platinum a Thunder Stone does not evolve Magneton: that came seven years later.
| Stone | Evolves | How common |
|---|---|---|
| Fire Stone | Vulpix → Ninetales, Growlithe → Arcanine, Eevee → Flareon | Far commoner with an odd trainer ID |
| Water Stone | Poliwhirl → Poliwrath, Shellder → Cloyster, Staryu → Starmie, Lombre → Ludicolo, Eevee → Vaporeon | Far commoner with an even trainer ID |
| Thunder Stone | Pikachu → Raichu, Eevee → Jolteon | Far commoner with an odd trainer ID |
| Leaf Stone | Gloom → Vileplume, Weepinbell → Victreebel, Exeggcute → Exeggutor, Nuzleaf → Shiftry | Far commoner with an even trainer ID |
| Sun Stone | Gloom → Bellossom, Sunkern → Sunflora | Commoner with an odd trainer ID |
| Moon Stone | Nidorina → Nidoqueen, Nidorino → Nidoking, Clefairy → Clefable, Jigglypuff → Wigglytuff, Skitty → Delcatty | Commoner with an even trainer ID |
The Odd Keystone, and the Pokémon behind it
The Odd Keystone is one of the scarcer finds worth having — like the old fossils it appears only after the National Pokédex, and it is the item behind Spiritomb. Put one in the Hallowed Tower on Route 209, then greet 32 different people underground, and it appears — as a wild battle at level 25, not a gift, so bring a ball. The tower tells you how close you are along the way, and the thresholds it speaks at are 8, 15, 22 and 29. Nothing else in these games gives you that Pokémon.
Everything else you will dig up
Almost two thirds of everything buried down there is spheres, which are not items you use but the currency other players’ shops take. The rest is a mix worth knowing about:
| Kind | Share of finds | Why you care |
|---|---|---|
| Spheres, five colours in two sizes | 63% | Trade currency for Secret Base decorations — no use in battle |
| Heart Scales, Revives, Star Pieces, Everstones, weather rocks, and a handful of other hold items | 14% | Move relearner, breeding and the weather teams of the era. The four named above plus the weather rocks are about 10% of that; the rest is Hard Stones, Rare Bones, Light Clay and the like |
| The six evolution stones | 9% | 21 evolutions across the three games |
| Red, blue, green and yellow shards | 7% | Move-tutor payment in Platinum |
| The seven fossils | 5% | The only Pokémon the Underground gives |
| 16 of Arceus’ plates | 2% | Change Arceus’ type, and boost that type’s moves |
| Seven kinds of worthless stone | 1% | Nothing at all — they exist to waste your wall |
- Which is better, Cranidos or Shieldon?
- Cranidos evolves into a hard-hitting attacker and Shieldon into a defensive wall, but you do not get to choose: your trainer ID decides. Odd IDs dig the Skull Fossil, even IDs the Armor Fossil, and the other one has a zero chance of appearing.
- Are there wild Pokémon in the Underground?
- No. Nothing can be encountered or caught down there. Every Pokémon the Underground gives you comes out of a fossil, or out of an item you dug up and used somewhere else.
- Can I dig up the same spot twice?
- Nothing in the Underground is placed in advance. Digging spots, spheres and traps are generated as you walk, per save file, so no map can tell you where to dig — only what the walls can contain.
- Is anything in the table impossible to find?
- Yes, one thing. The Oval Stone is listed among the buried items but carries a weight of zero in all four states, so the game will never bury it. It is a dead entry.