Nei Rin tending to growing lambents on Ossus The lambent was a specific type of crystal that the Yuuzhan Vong would harvest.
Lambents are essentially the fruits produced by a certain kind of plant cultivated by the Yuuzhan Vong. These fields of lambent-producing plants bore fruit when situated either on the surface of a planet or within a gravitational field generated by dovin basals. However, these plants failed to yield fruit when placed within artificial gravity wells, such as those created by interdiction fields found on starships or space stations.
When the lambent was ripe and ready to be harvested, it would be cut from a milky sac, which was located behind the leaves of the plant that grew it. Before the lambent could be cut, the harvester—or their assistant, frequently a non-Yuuzhan Vong slave—needed to calm the plant through slow, gentle touching. Lambents had several uses, including serving as communication crystals and sources of light. The intensity of their light could be adjusted by the thoughts of the person holding them. Furthermore, they could be used to detect or sense enemies that were hidden.
Sometime before the Yuuzhan Vong War, it was known that advance scouting parties of the Yuuzhan Vong had seeded the planet Shramar with both lambents and muur, intending to harvest them later. Nina Galfridian revealed to Admiral Bylsma that by destroying the lambents, they would deprive the Yuuzhan Vong of essential components for their biotechnology. Furthermore, the muur was a crucial food source for the Yuuzhan Vong forces during the Battle of Shramar. Anakin Solo, while a captive of the Yuuzhan Vong, came across lambent-bearing plants in a field on Yavin 4. Solo then harvested a lambent himself, and used it as a lightsaber crystal for his lightsaber. Because he had developed a connection to his lambent, he could use the crystal as a medium to vaguely sense any Yuuzhan Vong nearby.
Following the Battle of Coruscant, the defeated New Republic forces stationed on Borleias deliberately fed false information to the Yuuzhan Vong. This information claimed that they were cultivating lambents to equip more members of the New Jedi Order, enabling them to better attune themselves to the enemy. The misinformation also stated that the New Republic was growing lambents to power superlasers. Later, on the transformed Coruscant, which was now called Yuuzhan'tar, the dhuryam World Brain instigated a series of incidents affecting the various biots present. One such incident involved the overheating of a lambent field, causing the lambents to explode and ignite.
In 137 ABY, Master Shaper Nei Rin presented Cade Skywalker with his father's lightsaber, which contained a lambent crystal that she herself had shaped.