Gon Gon no Mi

The Gon Gon no Mi is a Paramecia-class that allows the user to convert various matter into different metals, which is furthered molded in the shape the user desires — akin to the principles of. This in-turn transforms them into a Metal Transmutating Human (金属変移人間, Kinzoku Heni Ningen).

Currently eaten by Regimel D. Elucifel, it serves as the reason for his epithet, "Metallic Alchemist" (金属錬金術師, Kinzoku Renkinjutsushi) — metal itself bending to his whims and becoming extensions of himself.

Appearance
According to Reggie, when he found the Devil Fruit in the depths of Rigdoria, it took the appearance of a very large cabbage head; however, unlike the rest of its kind, this one was silver in coloration and looked like aluminum foil. In addition, it had various cross-like patterns etched onto its surface — a common distinction between a normal fruit and a Devil Fruit; when he consumed it, he stated that it was rather bitter, have a mercuric texture, and was rather hard to swallow because of its density. Regardless, he gained its immense powers soon after, transmuting most of the landscape into pure metal without him realizing.

Trivia

 * The ideas for this fruit is based on — from its principles to its origins, and even its overall purpose; this would make the fruit the only one to employ another art to a certain extent.
 * According to Kaisei, the fruit is a stronger, more versatile variant of the Gutsu Gutsu no Mi, despite having very similar functions.
 * This fruit partly draws inspiration from the anime/manga series, Fullmetal Alchemist in various areas.