The Feejee (Fiji) Mermaid, an oddity from the mid-19th century that was made famous by P.T. Barnum and later mimicked by others.
It is a hoax that was typically made by sewing the top half of monkey to the tail end of a fish in a sort of gruesome taxidermy.
They were displayed to the public as actual mermaids, but was well known to be fake.
This skin is a representation of a more lively one, although it's eyes are still lifeless and I want it to look dried out.

A horribly disgusting monster, this example lives down in the depths of the sea, although can occasionally
be caught by eagle-eyed sea watchers perched up on rocks closer to shore.
Legends tell of them being caught in fisherman's net, frightening them half to death.
Curse upon the man who catches one and refuses to return it to the waters from whence it came.