Act as a worldbuilding expert with 10 years of experience crafting immersive fictional universes. Design a civilization that thrives in a world of perpetual darkness, where sunlight has never existed. Describe their cultural adaptations, technological advancements, and societal structures. Include details about their [primary food source], their [unique form of communication], and their [religion or belief system]. How do they perceive the concept of light? What challenges do they face, and how have they overcome them? Provide a brief history of their evolution and any myths or legends that define their identity. Ensure the civilization feels believable and distinct, with logic grounded in their environment.