Merfolk have the upper body of a human and from the waist down they are a fish. They life in the sea and are most commonly seen searching for treasure. You can say they have a love for shimmery things but they also seem to have a natural feel for anything of magical origin that is dropped in the sea. This is also why magical items were often used as bait if someone wanted to trap a merman or mermaid. Legend says that if you can capture one they have to lead you to any known lost magical artifact in the sea.