OMG!!!! I can never have an original thought😭 All jokes though, it's such a nice idea. Something like this is in the lore of a series I'm planning but I haven't gotten here yet.
It's a story about Witches, who wants it???
“So mermaids and sirens are two different species?” “Just so. My people, what you call mermaids or merfolk, share a common ancestor to you humans, making us distant cousins. What you call sirens, however, are fish that evolved to look and sound like humans to attract their favorite prey.”