The Paths of the Perambulator

The Paths of the Perambulator (1985) is a fantasy novel by American writer Alan Dean Foster. The book follows the continuing adventures of Jonathan Thomas Meriweather who is transported from our world into a land of talking animals and magic. It is the fifth book in the Spellsinger series.

Plot introduction
The strange world Jon-Tom has found himself trapped in takes a turn for the decidedly weird as Foster’s fantasy series take a page from Kafka's The Metamorphosis when the Spellsinger wakes up one morning as a giant crab. The cause, as determined by the turtle wizard Clothahump, is a trapped perambulator: an inter-dimensional creature that wanders through different universes leaving behind random changes to the fabric of the world. Jon-Tom and his friends attempt to free the perambulator before it wreaks permanent havoc on their world.