The Little Worm Book by Janet & Allan Ahlberg

The Little Worm Book by the well-known author/illustrators Janet and Allan Ahlberg, which was first published in 1979, is a tongue in cheek study of worms for little kids with a subversive sense of humour. It looks at the physical characteristics of a worm, worms as pets and what to look out for when buying your first worm, worms around the world, and worms in warfare. My favourite section is the main health hazards which a worm faces:

So if you want something light-hearted which would provoke a lot of philosophical discussion about worms, then this is a great book to share with anyone really, except maybe a blackbird. Just remember worms makes good pets, being more loyal than snails, much more fun than a slug and less liable to fly away than a ladybird.