The Smorg (Jap.: モアモア, Moamoa) are minor antagonists in Paper Mario: The Thousand-Year Door, being the main antagonists of Chapter 6.
The Smorg themselves are a species of small creatures about the size of a typical Fuzzy and resemble small dark clouds with yellow eyes and some of them are magenta. The Smorg can become a formidable threat when they congregate into a large mass of them and attack Mario and the other passengers, presumably with the intent to eat them.
This boss does not hold a Crystal Star, but it attacks the Excess Express during the ride to Poshley Heights. This boss is made up of a massive horde of smaller Smorgs and the base was made up of Magenta Smorg. They are first seen at the Riverside Station, where they lift the drawbridge to stop the train from going far (it is unknown if it is working for the Shadow Sirens to stop Mario and his teammates from reaching the Garnet Star).
Later on, they stow away on the train and kidnap the passengers. Mario and his teammates fight the Smorgs on the rooftop of the train to rescue the passengers. When they are defeated, they will blow away in the wind and release the passengers.
In the beginning of their fight, three tentacles will surround the main body, and near the end, they are replaced with a pincer claw that can do a large amount of damage to Mario and his partner.
Its name may come from the word "smog", based on its dark, cloudy appearance, and the term miasma, referring to a poisonous cloud and/or dangerous atmosphere, likely referencing the appearance (the "tentacles", specifically) and hostile nature of the Smorgs.
Smorg is the only chapter boss in Paper Mario: The Thousand-Year Door (with exception of the Shadow Queen) that does not possess a crystal star.
Earlier in the game's development, the Smorg were monsters created or tamed by Beldam who sicced them after Mario in order to halt his progress (they were supposed to fight the Shadow Sirens in Riverside Station after the Smorg battle), but this was cut in the final game, leaving no explanation for the Smorg's appearance.