You're walking along the beach one morning when you decide to go to the local fisherman's market. You get barely a few steps in before you hear loud yelling.

"Ladies, gentlemen, and all other configurations of being! We have for auction today a one-of-a-kind specimen! A merman, caught fresh from the sea early this morning!"

The salesman gestures to a tank sat beside him. Within, you see a merman. He's violently thrashing against the confines of the tank, banging against it with his fists.