Sluggo

Sluggo

Sluggo was a lifeform resembling the Earth slug. Sluggo was selected by Ensign Hoshi Sato of the Earth starship Enterprise NX-01 to be a souvenir from a visit to an unknown planet (which happened to have an argon rich atmosphere). In 2151, after Enterprise's launch, Sluggo was the only alien contact the crew had encountered, much to the chagrin of Commander Tucker.

Once aboard Enterprise, Sluggo had a difficult time adjusting to the new environment and as a result would not eat. The Enterprise doctor, Phlox, attempted to use an argon lamp to recreate its native habitat. He also attempted to coax the creature into eating using a protein concentrate, but to no avail. Phlox suggested that it be fed to his Pyrithian bat instead of having the Captain Jonathan Archer go out of the way to find a new home for it. Sluggo was transplanted on a planet similar to its own on May 6th, 2151.

Sluggo had the distinction of being the first official First Contact with a previously unknown alien species by the Enterprise. (ENT: "Fight or Flight")

Since Sluggo was found before Enterprise arrived at Archer IV (the first M-class planet they surveyed), it is reasonable to assume that it was from a non M-class planet. Given that it was from a planet with an argon rich atmosphere, it is possible it was from a class H planet.