Marlonia was a class M planet with an archeologically interesting history, inhabited by the Marlonians. It was considered by many to be one of the most beautiful planets in the entire quadrant.

The ancient Marlonian written language is often compared to ancient Taguan, but actually shares more similarities with ancient Buranian.

In 2369, Captain Jean-Luc Picard, Lieutenant Ro Laren, Keiko O'Brien, and Guinan spent shore leave on Marlonia, taking the shuttlecraft Fermi.

While on the planet, Captain Picard worked at an archeological dig, near some ancient Marlonian sites. He was permitted to take some pottery he found on the tertiary level of the dig, typical of second century Marlonian cookware, back to the Enterprise. Keiko spent her time studying the local fauna, and took home some samples of Draebidium calimus. (which is quite similar to another plant indigenous to Marlonia, Draebidium froctus) (TNG: "Rascals")