Here’s a top view of the Lightning Welk. The black part is the animal that is living in the shell. As it grows, it makes the shell larger in a spiral shape. It would have started out as the tiny piece at the center of the spiral, so you can see it has added a lot of shell over the years. The hard, thin piece on top of the animal is called the operculum. The animal can pull itself completely inside the shell and then the operculum covers the opening of the shell. The little girl with the family was delighted to be the one who put the Welk back in the water.