What's inside a clam? A retractable foot, a siphon for sucking up water, powerful muscles, and, sometimes, a pearl. And you thought oysters were fancy. Following is the transcript of the video.

The clam uses a tiny foot to burrow into the seafloor as it grows. Its shell can end up several feet down, with only its neck poking up into the water. Called siphons, these necks, double-barreled ...