Its appearance was first teased during the September Pokémon GOCommunity Day on September 22, 2018, and it was officially revealed on September 25, 2018.
Meltan without its head
Meltan is a small Pokémon with a silvery body of liquid metal. Its head resembles a golden hexagonal nut with small black sphere floating inside. This sphere serves as its eye. It has a red tail that resembles an electrical wire with two tiny protrusions at the end. Its body can corrode metal, which it then absorbs. Meltan can generate electricity using the metal it absorbs, and then fire it from its eye.
According to Professor Willow, Meltan has been described in ancient texts found in the same place as the Mystery Box, a mysterious item that attracts Meltan to its location when opened. Professor Willow also states that Meltan is said to be created when it splits from Melmetal. As seen in the anime, the hexagonal nut on its body can be removed. It has also been seen working in packs. When provoked, it will spin its heads, creating a sound that calls others of its own kind. This head-spinning can also be used as a sign of affection. The anime has also shown Meltan can be tamed if fed metal-like treats. Meltan is one of the smallest Pokémon, tying with Alolan Diglett and Klefki as the shortestSteel-type.
Multiple Meltan have made a number of appearances in the Sun & Moon series. Three first appeared in Evolving Research!, where they were briefly seen underwater, simultaneously marking the species' debut. Multiple Meltan were then seen inside the cargo hold of the ship that Ash and his classmates took back to Melemele Island at the end of A Grand Debut!. They currently live in the Ultra Guardians' base in the Pokémon School, where they assist Lusamine's Clefable in exchange for food. In SM124, they were revealed to have started multiplying, doubling the total number. In SM126, they were shown to have multiplied even further, raising the total number to 60.
This makes Meltan, along with its evolved form Melmetal, the only Pokémon in Pokémon: Let's Go, Pikachu! and Let's Go, Eevee! whose Kanto Pokédex number (152) is not the same as its National Pokédex number (808). While Kanto Pokédex numbers are normally used throughout the game, the judge screen displays National Pokédex numbers, which is evident for Meltan and Melmetal.
Meltan is the only Pokémon capable of evolution that cannot be evolved in the core series games.
In the anime, Professor Oak is the person who gives Meltan its species name.
Meltan may be based on a hexagonal nut, and its tail resembles an exposed wire. Its body is based on mercury, a metallic element that is liquid at room temperature. Mercury can also conduct electricity, as well as react with many other metals to form amalgams, which can hold a specific shape far easier than the pure liquid, hence Meltan's body.
Meltan may be a combination of melt, metal, and たん -tan (diminutive Japanese suffix). It may also be derived from tantalum or molten.