Cerean / Legends Cereans were a sophisticated and cultured humanoid mammalian species hailing from the planet Cerea in the Mid Rim . They were famed for their extraordinary thinking abilities , made possible by large binary brains housed in tall tapering heads , enabling them to focus on many things at the same time . Aside from this unique feature , Cereans were physically similar to Humans , although they each possessed two hearts , which supplied extra blood circulation to support their brains . Cereans were often found among the ranks of the Jedi Knights , but due to the species ' low birth rates , Cerean Jedi were exempt from the Order ' s vow of non - attachment . One such Jedi , Ki - Adi - Mundi , served on the Jedi High Council during and prior to the outbreak of the Clone Wars . Biology and appearance . The Cereans ' enlarged skulls , extending up to twenty centimeters above their foreheads , housed complex binary brains , provided with sufficient blood by an extra heart in their heads . The binary structure of Cerean thinking helped them to ponder two sides of an issue at once . It also enabled them to process information and solve problems rapidly and provided a highly advanced capacity for concentration and meditation . Because of their thoughtful nature , they tended to be calm , rational and analytical , preferring peaceful philosophies and a lifestyle which worked in harmony with nature . Though the quick - thinking Cereans had equally quick reflexes , they were commonly not as well coordinated as Humans . Because of the weight of their enlarged skulls , Cereans often had back problems and were less physically coordinated than the average Human . Cereans were a sexually dimorphic species , with male Cereans aging more rapidly than their female counterparts . Additionally , males were outnumbered by females due to a skewed birth rate ratio of twenty females to every one male . Force - sensitivity among Cereans was similar to that of baseline Humans , with Cereans training as both Jedi and Sith . Their binary brains , it was suggested , allowed some Cerean Forcefuls to explore both the light and dark aspects of the Force . Society and culture . Cereans developed a low – tech society on their homeworld and preferred to live in isolation from the wider galaxy . Preserving the natural beauty of Cerea , the planet was home to many Outsider Citadel s where it was permissible to use offworld technology , though it could not be removed from the Citadel . Beyond the Citadels , offworld technology was strictly prohibited , especially that which could harm the planet ' s ecoystem . Meditation was a core part of a Cerean ' s daily rituals , with many employing specially - forged kasha crystals as a focusing tool . By focusing one ' s thoughts while in contact with such crystals , distractions were eliminated , creating an exceptional meditation environment . Cerean Jedi sometimes incorporated these crystals into their lightsabers , providing great focus , even during intense physical combat . Because of the dimorphism in the species , the government of Cerea was matriarchal . The governing Council of Elders was led by a president who made decisions based on the advise of the Council . Decisions made by the Council were considered to be infallible and appeals were unheard of . During the years leading up to the Invasion of Naboo , a generational dispute erupted on Cerea when the younger generation took up a rebellious stance against their low – tech society . Many Cerean youths wished to own such technology as was commonplace in the Galactic Republic , like starships and speeder bikes . This unrest was ultimately quelled by Jedi Knight Ki - Adi - Mundi , who traced the instigator of the movement , Ephant Mon , to Tatooine . The traditional nature of the Cerean community was reflected in their names , which were broken into three hyphenated parts . The names were derivatives of an individuals parents and grandparents . The clothing worn by most Cereans was based on a traditional style that carried on over the centuries . Martial arts was a focused and stylized part of many Cereans ' lives , with the use of the ancient shyarn as a means of moving through aggression . Polygamous marriage was a necessity in order for the species to survive , due to the dimophism in the sexes . Each male usually had one primary " bond - wife , " and between four and ten " honor - wives . " Culturally , Cereans embraced the Force and their knack for analysis allowed them insight that resembled precognition . Cereans in the galaxy . Ki - Adi - Mundi served as Jedi Watchman for his home system , though he relinquished this post during the Clone Wars to fellow Cerean Tarr Seirr . When Seirr was also called away , the Cereans were left undefended and their planet was attacked by the Confederacy of Independent Systems . The death toll of the Battle of Cerea reached over one million , and included the family of Ki - Adi - Mundi . This led to the Cereans becoming even more removed from galactic affairs with the rise of the Galactic Empire . By the time of the Yuuzhan Vong War , the Cereans had developed a unique Force tradition , known as the Ner Yan . This group used the Force to link their minds , although in a haphazard manner . Ka - Tu - Un was an adept of this tradition and was mistaken for a Jedi by the Yuuzhan Vong .