Prompt: A group of smooth, polished river stones of varying sizes and shapes arranged in a spiral pattern on a flat grey concrete surface. The stones range in color from light grey to dark charcoal, with some stones showing flecks of white quartz. The spiral pattern begins with larger stones at the outer edge and gradually decreases in size toward the center, creating a natural mandala-like formation. Each stone's surface reflects ambient light, highlighting their polished, worn texture. Close-up photography with soft natural lighting and sharp focus on textural details against a neutral background.