Both the Dome and Helix Fossils appear on the artwork for the Mysterious Fossil card. The two Fossils were later split off into their own individual cards.
Related cards Cards listed with a blue background are only legal to use in the current Expanded format. Cards listed with a silver background are legal to use in both the current Standard and Expanded formats.
In the first Pokémon Red and Blue run of Twitch Plays Pokémon, the chaotic control scheme resulted in the player constantly using the Helix Fossil. This lead to jokes that the game's protagonist was constantly consulting it for advice. This resulted in memes that the player worshiped the Helix Fossil and fans referred to Omanyte as "Lord Helix".