When a chicken lays an egg, its child is only protected from the dangers of the world by a thin fragile shell. How much better the protection would be if the egg were to be encased in solid rock. Of course, when the young chick grows and is ready to face the big wide world, that excessive protection now becomes a problem and may even prevent it escaping. This saying therefore describes over-protective parents. The English equivalent uses the opposite imagery. To wrap someone (or something) in cotton wool.