"'Feejee Mermaid' has become the generic term for the many fake mermaids that can be found around the world..."
This article contains information relating to a hoax. According to Cambridge dictionary a hoax is "a plan to deceive a large group of people; a trick."
The Unknown Fish is a strange looking fish reportedly caught on a beach in Tampa Bay, Florida back in July 2006. The photos have widely circulated on the internet. It has been proved to be a hoax, though the maker of the hoax says that it was based on a real fish. The fish was sold on eBay for a winning price of $637 under the name: mummified sea monster corpse.