Michiko Watanabe, age 11, Of San Francisco, Calif., for his question:

How are baby snails born?

A snail lays a package of small round eggs on the ground. Several packages often are left in the silvery, slippery trail behind a crawling parent. The eggs mature and the embryos develop miniature shells like tiny fragments of glass. The little hearts begin to beat, and in a week or so the young snails emerge. As a rule, they eat their own egg shells. Then they crawl off to find other snail food.

The family life of a snail is extraordinary. Each parent is both a mother and a father. Two of them mate and go their separate ways. Later, both lay batches of eggs. But each is the father of the youngsters produced by the other parent. Young snails never know their parents. Hence, they never have to settle their unusual relationships to other young kinfolk.