Nacli is a Pokémon composed of rock salt. Its upper body is rugged and brown, with an off-white stripe circling it, while its lower body is a white salt cube with rectangular orange-yellow eyes that can glow red. A white salt cube is embedded on the top half of its body as well.
Nacli are born deep within the earth, inside layers of rock salt. Bits of salt are scraped off of Nacli as it travels the ground, although Nacli is able to create and replenish the salt inside its body. In the past, Nacli was treasured by people who would use its salt. Even today, Nacli salt is still used in foods such as ice cream, because it has a gentle flavor.
Nacli and its evolutions are the only known Pokémon that can have Purifying Salt as an Ability.
Nacli is based on a rock salt crystal embedded in a small sedimentary rock. Its body shape resembles mushrooms, particularly those of the Agaricus bisporus variety. Considering it is originated underground, it might also draw inspiration from truffles. Additionally, its mushroom shape may be a reference to mushroom rocks, which are naturally occurring rock formations.
The scraping of its body along the ground leaving salt trails might be a literal interpretation of salt roads, trade routes upon which salt was transported to foreign markets. Its glowing eyes may be based on Himalayan salt lamps.
Nacli may be a combination of NaCl (chemical formula for sodium chloride; table salt) and little. The -i at the end of its name may also refer to iodine, a common element added to salt to prevent iodine deficiency. It may also be a pun on salty (the taste or usage of salt).
Kojio may be a combination of 小 ko (small) or 子 ko (child), 塩 shio (salt), and geo- (prefix for earth).