"Oh, very nice," Sam said, taking the shell. "It's very rare to find both valves of a bivalve mollusk intact and undamaged." She turned it over, admiring the coloration, and as she did it made a little rattling sound.

A little rattling sound like the sound of metal against the calcium-rich shell.

She shook it again, gently, just enough to hear the sound of it again, and then looked up at him.