This was so much fun to do. Essentially it's just a massive drugged up fat, fleshy mass on a mushroom. I'd like to go on about how it's so much more than that. But it's not.
Interesting Fact: The face of the caterpillar is based on Johnny Vegas. Except without a nose. The character 'Moz' he plays in the sitcom 'Ideal' summed up my representation of the caterpillar in the story perfectly.