"There's something alive in here."
―Luke Skywalker
Dianoga were large cephalopods, capable of growing up to ten meters in length, though most specimens grew to approximately five or six meters. They had a single eyestalk protruding from their mollusk-like bodies, and seven suckered tentacles surrounding a fanged maw containing a sharp serrated probe.
Dianoga originated on the planet Vodran—discovered by the Hutts prior to the formation of the Galactic Republic—where the creatures evolved a form of natural camouflage to disguise themselves and avoid the planet's large predators. Their bodies would become transparent when unfed, and, conversely, were known to change to reflect the color of the food they had eaten. This was achieved by diverting small portions of digested food into a series of ducts underneath the creature's skin, which would appear to affect the color of the dianoga's flesh. Over many millennia, dianoga migrated from Vodran by stowing away aboard garbage ships in their microscopic larval forms, and could be commonly found in trash compactors, garbage pits, and sewers across the galaxy, living off any present organic matter. They were primarily scavengers, and only posed a threat to living creatures when starving or threatened. Because of their penchant for living in and feeding on organic waste, dianoga were sometimes referred to as garbage squids, sewage squids, or trash monsters. Dianoga would often prove a nuisance by nesting in bodies of water, sewage systems, and whatever other large concentrations of dirty, appalling liquid that they could locate. Smaller dianoga were even known to crawl out of toilets. Despite this, they could prove useful, since they served to rid waste of biological material, leaving behind salvageable minerals and metals. Only when a dianoga grew too large was it usually considered a threat, especially in urban areas such as Galactic City on Coruscant. Indeed, in 22 BBY, Coruscant's Desrini District experienced a dianoga infestation, following an incident with a misfiring garbage launcher. Up to twenty-five residents were reported to have been attacked by the scavengers, and it was believed the creatures would quickly spread to neighboring districts. The presence of a single dianoga was often cause for alarm, since the creatures were self-fertilizing hermaphrodites, and could quickly multiply to pose a larger problem.