Lekku

Lekku (singular lek), also referred to as head-tails, were long, fleshy appendages that protruded from the head of all Twi'leks and Togrutas. The former species had two (occasionally four) lekku, while the latter sported three of them.

In Twi'leks
In Twi'leks, lekku were shapely prehensile tentacles that grew from the base of their skulls. While Twi'leks normally had two lekku, certain individuals like Orn Free Taa had four of them. Those organs were very sensitive to touch, and a damaged lek could cause severe harm to a Twi'lek. In addition to their spoken language, Ryl, the Twi'leks could also communicate through subtle lekku gestures.

Despite the high sensitivity of those organs, some Twi'leks like Cham Syndulla tattooed their lekku. Some wore them simply hanging down their back or falling over the chest, while others like Bib Fortuna bent them around the neck or shoulders for aesthetic purposes.

In Togrutas
The name "lekku" was also used to describe the striped head-tails of the Togrutas. That species, however, had three such appendages: two lekku to the front, falling over the chest, and one thicker lek that was centered at the rear base of their skull. The lekku of a Togruta would become longer with age. A male Togruta's front two lekku were shorter than those of a female. The color of a Togruta's lekku was determined by their DNA.