The Unlucky Snails Go to New Zealand — Wendy Hamilton

Shelly and Sluggo feel the need to grow bigger because of a difficult neighbour, so they go to New Zealand in search of giant kauri snails. Their quest is unsuccessful until a naughty magpie introduces them to a 'snail' called Rugby. After a shocking encounter with Rugby's life, Shelly and Sluggo decide their troubles are not as big as they first thought.