In 2370, Doctor Mora Pol of the Bajoran Institute of Science mounted an expedition with Starfleet assistance to L-S VI, where Bajoran science probes had discovered DNA similar to Odo's. Silicate-based lifeforms were found on the planet, including a small vegetative organism with Changeling-like metamorphic properties.
During the expedition, Jadzia Dax, Mora Pol, and Weld Ram were injured from inhaling a ground eruption of volcanic gas. Odo was also unknowingly affected by the gas, which caused him to change into a large, instinct-driven creature, back aboard Deep Space 9. (DS9: "The Alternate")
Background Information Edit
L-S VI was depicted using a set on Paramount Stage 18. "We [...] had to shoot a planet set," recalled David Livingston. "I think David [Carson, the director,] and [DP] Marvin [Rush] shot it successfully; you really believed you were on this ruined planet. It's hard to do that kind of stuff." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 68)
It is unclear whether the obelisk which, in "The Alternate", is found at the center of the ruins on L-S VI and described by Mora Pol as a possible "relic of Odo's people" was indeed genuine. "To tell you the truth," admitted Odo actor Rene Auberjonois, "I think the obelisk was simply a red herring. In fact, I asked [director] David Carson if anything is going to happen with this thing and he just grinned and said it's just a red herring to confuse the audience so they don't get too far ahead of us [....] But I never assume anything. Watch, three stories into next season there will be a whole story about the damned obelisk still floating around the station." (Cinefantastique, Vol. 25/26, No. 6/1, p. 103) In fact, the obelisk is almost identical to one seen on the Founders' homeworld in DS9: "The Search, Part II", the second installment of the season following "The Alternate".