Exogorth

Space slugs reached full maturity at ten meters and reproduced by splitting into two smaller, separate bodies. If a space slug was incapable of this process, its growth continued uninterrupted, potentially reaching lengths of 900 meters. Slugs of this size were known to swallow starships whole and house entire ecosystems among their gut flora.

Favoring life in asteroid fields, space slugs would burrow into an asteroid until completely hidden. From there, they fed on stellar energy emissions, mineral-rich deposits from the asteroid, floating space debris, and (supposedly) other silicon-based creatures, such as mynocks. Largely dormant, the opportunistic feeders would lie in wait for sources of sustenance; if they weren't resting with their gaping mouth disguised as a crater or tunnel (to trap unwitting victims), the space slugs were capable of periodically lunging from the asteroid's surface at passing ships. However, this was not their preferred attack method; doing so could be quite physically demanding, leaving them over-exerted and exhausted for a time.

Space slugs could live unbelievably long lives. Sy-O, the creature that resided within the Hoth asteroid belt, was estimated to have aged over a billion years by the time of the Galactic Civil War; this was considered young.

The flesh and blood of an exogorth were red, while its saliva was green. Exogorths had mouths with 45 teeth.

Exogorths were a patient and relatively peaceful species that prided themselves on their ability to have their bodies become stable ecosystems, home to countless species that peacefully co-existed. Exogorths that hosted varied, diverse ecosystems in their bodies were considered highly respectable. By comparison, those who lacked a variety of lifeforms in their gut ecosystems, or only maintained non-sentient, "lower" lifeforms (such as mynocks, as Sy-O had), were looked down upon, to not host anything of a higher sentience (or more relevant galactic importance) was considered "lacking", and projecting a poor self-image.

The species was described and known already for more than a billion years; Sy-O, who was himself billions of years old, was considered young for the species.

After an attack on a rebel base during the Galactic Civil War, a conflict between the Alliance to Restore the Republic and the Galactic Empire, Commander Tylux of the Imperial Navy ordered his Imperial-class Star Destroyer, the Bellicose, to pursue an escaping rebel spy in order to not fail the Sith Lord Darth Vader. Eventually, the Bellicose lost its entire wing of TIE fighters in a failed pursuit of the rebel's UT-60D U-wing starfighter/support craft, yet Tylux continued the chase into an asteroid field. After the rebel's protocol droid Exo spotted an Exogorth ahead of them in one of the asteroids, the rebel flew his U-wing into the creature to attempt to get away. To the horror of one of his Imperial officers, Tylux ordered his Star Destroyer to pursue the U-wing into the beast; the Bellicose rammed into the Exogorth's mouth and through it, forcing the rebel to fire on the creature to try to escape. Bursting through the Exogorth's skin after the U-wing, Tylux understood he had the rebel trapped, only to learn mynocks from inside the creature were spreading damage on the hull of the Bellicose, making one of his officers incorrectly speculate the rebel had led them into the exogorth as a trap. As the remains of the exogorth floated nearby, the crew of the destroyer were forced to abandon the starship after rebel reinforcements arrived.

After the Battle of Hoth, the Millennium Falcon, unable to jump to lightspeed due to its damaged hyperdrive, fled pursuing TIE fighters by hiding inside (what its crew believed to be) the crater of a large asteroid, known simply as the "Big One." In reality, the tunnel was the gaping maw of the giant space slug, Sy-O. Inside, they tried to repair the Falcons hyperdrive. While sitting in the cockpit, Leia Organa was alarmed by a mynock flying outside, so she stepped outside with Han Solo and Chewbacca to investigate. When shots were fired, Sy-O lurched in a manner that made the group think that the "cave" was collapsing, or perhaps an earthquake tremor was occurring. However, Solo, silently realizing where they actually were, ordered everyone back in the ship and flew the Falcon directly out, between Sy-O's closing teeth. They escaped unharmed, before the space slug completely closed its mouth. Sy-O attempted to lunge, and snapped his jaws at the Falcon (in hopes of keeping the crew inside and expanding his gut ecosystem); the freighter was too fast for him, so Sy-O receded back into the crater. After the Falcons departure, one of the pursuing TIE fighters was attacked by Sy-O, forcing the pilot to eject into space. The accompanying members of the TIE squadron concentrated their attack on the slug, chipping its tooth and eventually forcing it to recede once more into its hideout.

While being chased in the Y'Toub System by the bounty hunters Zuckuss and 4-LOM aboard their starship Mist Hunter, fellow hunter Beilert Valance flew the Corona-class armed frigate that he had stolen with another hunter, Dengar, into an asteroid field inhabited by a number of exogorths. As the exogorths reached out of their asteroids, the Corona escaped the Mist Hunter.

The exogorth first appeared in the 1980 original trilogy film Star Wars: Episode V The Empire Strikes Back. Concept art of it was made by Ralph McQuarrie. The exogorth was identified in the 2015 reference book Star Wars: Absolutely Everything You Need to Know.

Huge slabs of beef fat and dozens of raw eggs being walked on were used to create the squelchy sounds of the Millennium Falcon crew's footsteps as they trudged inside the exogorth in The Empire Strikes Back.

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