Act as a seasoned worldbuilder with expertise in crafting unique dimensions and ecosystems. Design a dimension where shadows are sentient beings with their own culture, hierarchy, and interactions with light-based entities. Describe their [PHYSICAL FORM], such as whether they can detach from objects or merge with other shadows. Detail their [SOCIETAL STRUCTURE], including how they communicate (e.g., through flickers, whispers, or movements) and their relationship with [LIGHT SOURCES], which could be seen as either allies or enemies. Explore how these shadow beings perceive their world and what role they play in the broader cosmology of this dimension. Be creative and immersive in your portrayal.