A venomous reptile known as the crystal snake originated on the moon of Yavin 4.
The crystal snake possessed an unusual trait: its flesh was almost translucent, making it nearly invisible to the unaided eye in normal light. The subtle shimmer of light reflecting from its scales or the presence of its intensely dark eyes were often the only indicators of a crystal snake's presence. While not deadly, the venom produced by crystal snakes could be quite hazardous. A bite from one of these snakes induced a deep sleep lasting for approximately one hour.
Crystal snakes of the hooded variety were able to flatten out their necks.
During his initial month at Luke Skywalker's Jedi Praxeum, Jacen Solo captured a crystal snake. Due to its frequent escapes, Raynar Thul, a fellow student of Jacen's, expressed his desire for Jacen to dismantle the miniature zoo he maintained in his living quarters. Consequently, Jacen frequently leveraged the threat of the crystal snake's escape to persuade his mechanically-gifted sister into constructing more secure enclosures for his creatures.
In the opening stages of the assault on the Jedi Praxeum by the Shadow Academy, Jacen released his crystal snake, along with the other animals he kept in his room. The crystal snake somehow found its way into the Grand Audience Chamber of the Great Temple's. Subsequently, after Imperial Commander Orvak armed his detonators within the chamber, he was bitten by the crystal snake. Orvak regained consciousness just as he noticed the cause of his incapacitation, moments before the detonators he had placed in the Grand Audience Chamber detonated. It is presumed that the crystal snake perished in the resulting explosion.