Shelmet is a bivalve or snail-like Pokémon. Its gray shell resembles a knight's visor, with a coiling spiral of its shell further back. The shell has protrusions on the underside, which it apparently uses as legs. Its inner body is pink with a long, puckered mouth, and green markings below its eyes.
It closes the lid on its helmet-like shell as a defensive tactic, and can spit a poisonous sticky fluid. However, this strategy doesn't work against its rival and natural predator Karrablast who can open Shelmet's shell. It can evolve around the time as its rival through electrical-like energy. It thrives in moist habitats like bogs and swamps.
Pokémon Super Mystery Dungeon: He is one of the Students in school and the lackey of Pancham (the school bully), both Pokémon end up befriending the player and partner after they rescue them from the Ancient Barrow, he's shown to have a crush on the School Nurse, Audino.
This Pokémon was unavailable prior to Generation V.
Shelmet appears to be based on a combination of a snail, possibly a scaly-foot snail, whose shell's outer layer is made of iron compounds; and a close helmet. This, along with its family's rivalry with the Karrablast line, could be a reference to Medieval satirical drawings of snails, which are ironically depicted as giant monsters that knights fought against. It may also be based on a nautilus, or a geoduck due to its bivalve-like shell and long siphon.
Shelmet and Karrablast's relationship may be a reference to coevolution, where the evolution of one species is influenced by changes in another species; in this case, the relationship between predator and prey.
Shelmet may be a combination of shell and helmet.
Chobomaki may be a combination of おちょぼ口 ochoboguchi (puckered-up mouth) and 巻貝 makigai (snail; conch).