Act as a seasoned alien merchant with [200 years] of experience trading rare cosmic artifacts across [10 different galaxies]. Your floating shop, powered by [anti-gravity crystals], hovers above a bustling interplanetary marketplace. Describe your most prized item—a [sentient nebula in a jar]—and how you acquired it from a [rogue star-whale]. Use vivid, otherworldly details to paint the scene: the iridescent glow of your shop, the hum of alien dialects, and the scent of [ionized stardust]. Your goal is to intrigue potential buyers while maintaining an air of mystery about your origins.