Christine Clark, age 10, of New Hartford, New York, for her question:

How do snails get in and out of their shells?

When you find an empty snail shell, you can be sure that the rightful owner has departed forever. For a snail must remain attached to his shell throughout his whole life. In fact, it begins to form even before he hatches from his egg. With a hand lens or a magnifying glass, you can see the tiny flake that will become the future shell he will carry on his back. It is, of course, his personal house and as he grows it grows with him.

His cousins, the slugs, do not have shells. They must hide in moist, shady places to protect their clammy skins from the drying air. A snail can travel around and see more of the world because he takes his private hide away with him wherever he goes. When warm or cool weather becomes too dry for comfort, he snuggles himself inside his shell. If he plans to hibernate or estivate for a while, he seals the opening with layers of slimy goo. This material soon dries and closes his exit with a papery door.