If brought to the one of the following locations, the Helix Fossil can be regenerated into an Omanyte.
Generation I and III
In the Generation I and III games, the Helix Fossil is a Key Item.
In Pokémon Emerald, the Helix Fossil (as well as the Dome Fossil and Old Amber) is found in the game data, but it is not legitimately obtainable and has no effect. The player is unable to regenerate this fossil in the Devon Corporation.
Generation IV onward
From Generation IV onward, the Helix Fossil is no longer a Key Item, and is a normal item. Therefore, multiples of them can be obtained, they can be held, and sent to other players via trading.
||A fossil of a Pokémon that lived in prehistoric times.
||A piece of ancient marine Pokémon's seashell.
||A fossil of an ancient, seafloor-dwelling Pokémon. It appears to be part of a seashell.
|A fossil of an ancient Pokémon that lived in the sea. It appears to be part of a seashell.
|A fossil from a prehistoric Pokémon that once lived in the sea. It might be a piece of a seashell.
- Main article: Helix Fossil (Majestic Dawn 91)
The Helix Fossil was introduced as a Trainer card in the Pokémon Trading Card Game in the Majestic Dawn expansion, first released in the Japanese Moonlit Pursuit expansion. Although it is a Trainer card, it is played as if it were a Colorless-type Basic Pokémon, meaning the player's opponent takes a Prize card when it is Knocked Out. However, Helix Fossil can't be affected by any Special Conditions, can't retreat, and the player may choose to discard it at any time during their turn. When the player attaches a Water Energy from their hand to the Helix Fossil, they get to search their deck for an Omanyte that evolves from a Helix Fossil and put it on top of it. Afterwards, the player shuffles their deck.
During the XY Series, the Fates Collide expansion included the Item card Helix Fossil Omanyte. It allows players to look at the bottom seven cards of their deck, reveal an Omanyte they find there, and put it onto their Bench. The other six cards are then shuffled back into the deck. The Scarlet & Violet Series saw the release of Antique Helix Fossil in the 151 expansion. This card is similar to the original Helix Fossil, as it is played as a Basic Pokémon, evolves into Omanyte, can't retreat, is not affected by Special Conditions, and may be discarded at any time during the player's turn. In addition, it blocks the opponent from playing any Stadium cards from their hand, as long as Antique Helix Fossil is in the Active Spot.
Helix Fossils are also featured on the Mysterious Fossil, Buried Fossil, and Unidentified Fossil cards. All of these cards are played as if they were Basic Pokémon and can evolve into Omanyte.