Children up to the age of seven are like sponges. They look up to adults and copy what they do. So I thought if I could create a positive role model - a superhero, if you like - who moves around and has a balanced lifestyle - then they would be motivated to move more.

I'm a writer who stacks cat food for a living. It's true: I have a master's degree in creative writing, I've published two critically successful books, and I get paid to replenish the shelves of my local food co-op with pet food, sponges and toilet paper. Nine days out of 10, I do it quite happily.

A sponge is a funny animal to center a show on. At first, I drew a few natural sponges - amorphous shapes, blobs - which was the correct thing to do biologically as a marine science teacher. Then I drew a square sponge, and it looked so funny.

Children are like sponges; they start to smell after a little while.