A volcanic Gamma Quadrant planet where a Bajoran probe detects DNA patterns resembling Odo's, prompting an expedition that brings back a stone pillar, a tiny lifeform and a dangerous gas.
L-S VI is a planet in the Gamma Quadrant, a few light years from the wormhole, visited in The Alternate.
Doctor Mora Pol, the Bajoran scientist who studied Odo, arrives at Deep Space 9 with news that a probe has found DNA similar to the Changeling's on the planet. Odo, Mora, Jadzia Dax and the Bajoran scientist Weld Ram travel there by runabout and find the ruins of a vanished civilisation, a carved pillar and a small shapeshifting organism.
When the team beams the pillar away, an earthquake releases volcanic gas that overcomes everyone but Odo. The gas turns out to have affected him after all, causing him to transform into a violent creature aboard the station while he rests.