That sounds like a gentle lullaby for the tides. Start with the smallest note, a soft hum that rises with each shell’s curve, and let the pitch swell as the spiral expands—like a breath that catches. Use the Fibonacci ratios as intervals: a minor second for the first turn, a major third for the next, then a perfect fifth, echoing the shell’s quiet rhythm. It’ll feel like the sea itself singing a slow, resonant song that grows just as the shell does.