Your 兄 elder brother has two trident-shaped 丷 horns sticking out of his head. Why are they in the shape of tridents? Because he is a 兑 merman of course. You haven't met many 兑 mermen with 丷 horns before, but you feel that most 兑 mermen probably should have 丷 horns shaped like tridents. Just like the trident Neptune has.