The Shell Exchange is the story of a hermit crab named Matty, who runs a shell exchange for hermit crabs needing larger shells. The story is set near the Ningaloo Reef in Western Australia. Matty is helped by Occy the blue-ringed octopus, who runs the banking part of the business.

There are encounters with many of the marine creatures living in this part of the world, including anemone, sea-slugs (some of which are very beautiful), snails (whose empty shells are used by hermit crabs), fish and soldier crabs, as well as with humans.

The story is illustrated with photographs taken by the author. There is an extensive reference list and glossary included for children who would like to learn more about this beautiful and fascinating place and its inhabitants.