An engraving of Koch’s “Hydrarchos”, from the American Phrenological Journal. (Pardon the smudges)

In July of 1845 the amateur fossil hunter Albert Koch brought his sea monster to New York City. A cousin of the serpentine creatures that so many had claimed to see off the coast of New England, the 114-foot-long skeleton looked to be the bones of the Leviathan itself, and crowds flocked to see the its ghastly form. It was called “Hydrarchos” by Koch, and it was was the ruler of the ancient seas.

It was also a monstrous hoax. The Hydrarchos skeleton did not belong to any one animal but to several, and much of its skeleton represented an animal that had been described