Book excerpt: Stephen Jay Gould borrowed from Winston Churchill when he described the conodont animal as a "riddle wrapped in a mystery inside an enigma." This animal confounded science for more than a century. Some thought it a slug, others a fish, a worm, a plant, even a primitive ancestor of ourselves. The list of possibilities grew and yet an answer to the riddle never seemed any nearer. Would the animal that left behind these miniscule fossils known as conodonts ever be identified? Three times the animal was "found," but each was quite a different animal. Were any of them really the one? Simon J. Knell takes the reader on a journey through 150 years of scientific thinking, imagining, and arguing. Slowly the animal begins to reveal traces of itself: its lifestyle, its remarkable evolution, its witnessing of great catastrophes, its movements over the surface of the planet, and finally its anatomy. Today the conodont animal remains perhaps the most disputed creature in the zoological world.