Dianoga were sentient cephalopods characterized by seven suckered tentacles, an eyestalk, a mouth of sharp teeth, and several hearts. They could grow to a length of 7 to 10 meters. Their blood had a blue tint.
Although they could survive in the open air for short periods of time, dianoga were entirely dependent on water, lest they completely dried out.
While physically hermaphroditic, dianoga could choose to identify as female, diangous (the most common gender), or male. The mating process involved partners exchanging eggs with one another.
The normal skin color of a mature individual was a deep purple, but dianoga could change their color and patterns for active camouflage. They could notably turn black, gray, and even transparent. They also had the ability to regenerate lost limbs.
Dianoga were omnivores, feeding on smaller animals like fish and crabs, but also feed on bones and aquatic plants.
Did you know that the dianoga was originally meant to be much different in Star Wars? Lucas envisioned it as a semi-transparent, enormous monster with some kind of magical powers. It had to be scaled down more and more throughout production until it was just a tentacle and an eye. But the dianoga’s story in From a Certain Point of View actually preserved some of its mystical, Force-based elements forty years after the film’s release.