A museum specimen of particular note was a fossil, the Hydrarchos or Zeuglodon, which the Complete Guide to the St. Louis Museum called "the greatest fossil in the world." The Zeuglodon was constructed mainly from basilosaurus fossils discovered in 1848 in a field in Alabama. After they were extricated from the rock in which they were found, Dr. Koch purchased the fossils for the St. Louis Museum. The fossils were shown to Yale chemist Benjamin Silliman, likely before being rearranged by Koch. Silliman, who had recently lectured on the basilosaurus, wrote a letter to Koch about his find. A broadside promoting the exhibit took Silliman's letter out of context and presented the hydrarchus as "Leviathan of the Antediluvian World". Professor Joseph Leidy also attested to the authenticity of the fossils, though it's not clear if he saw them before or after Koch's rearrangement. Professor Jeffries Wyman eventually exposed the hoax, and Silliman wrote another letter to Koch asking not to be associated with the exhibit. The hydrarchos continued to be displayed and was taken by Koch to Dresden, where it was destroyed by Allied bombing of that city during WWII. A smaller model was destroyed in the Great Chicago Fire.