Outwardly, Zelosians were nearly identical to Humans in height, build, hair and skin pigmentation, and their ability to grow facial hair. Because of this, Zelosians could keep their origins a closely guarded secret and were commonly misidentified as Near-Humans by outsiders. While their resemblance to humans had been suggested by some as a spectacular form of naturally evolved mimicry, many Zelosian biologists believed that their species was the product of genetic engineering, though there was no direct evidence to support this. Thus, unlike many true Near-Humans, Zelosians were not known to be able to interbreed with any other humanoid race as it was quite hard, but not impossible, to conceive.
Because of their unusual ancestry, Zelosians possessed a number of plant-like characteristics. Their blood was a green chlorophyllic sap. Additionally, a large portion of the muscles of Zelosians were cellulose fibers, with some form of nastic response apparently being involved in their reflexes. Zelosians still consumed vegetable and animal product-based foods, but could also photosynthesize through their skin. Celot Ratua Dil believed that he could survive one to two months on only sunlight and water.
All Zelosians possessed emerald-green eyes. They were also night-blind, being unable to see whatsoever in light dimmer than that provided by a full moon. This meant that they stayed indoors after sunset and held many superstitions about the night (although their suspicions about zombies proved to be somewhat true, being actually caused by corpses reanimated by parasitic worms known as jumpers).
Alcohol had no intoxicating effect on Zelosians. However, refined sugar had a comparable one; a tablespoon would have affected Zelosians as four ounces of strong liquor might affect a Human.
Zelos II was subjugated by the Galactic Empire for ore mining, but the Zelosians were kept ignorant that the mining work they did supported the Imperial war machine. After the Battle of Endor, the Zelosians believed the Imperial military had abandoned Zelos II, not knowing of a hidden base in the Valley of Umbra; the New Republic sent in forces to take out the base, but walked into an ambush. In the wake of the seeming Imperial abandonment of the planet, Zelosian Galleros Nul declared martial law, making himself Mandated Commander of the People of Zelos. When the Imperial presence on Zelos II was exposed by Jai Raventhorn, Nul disavowed the Empire entirely and petitioned entrance for his world to the New Republic.
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