The alien-looking specimen below is a 'Jenny Haniver' - a dried and lacquered skate fish manipulated to resemble a fantastical creature of the deep or 'sea devil'. Another example of faking monsters is the (in)famous 'Feejee Mermaid' - a rather unlovely combo of orangutan and salmon carcass exhibited as the authentic remains of a mer-person!
A Jenny Haniver Fish
The Feejee/Fiji Mermaid
There is an extraordinary 'museum' of fake mutants here created in homage to the freakshow theatrics of the Feegee mermaid and her many imitators. If you click on the numbered titles, on the left of the site, you'll be taken to various floor plans of the museum. Click on the 'rooms', and you'll be shown collections of chimeras. The attempt to render these 'remains' as credibly as possible - as actual dessicated specimens presented as 'real' - blurs the line between fact and fiction deliciously.