in mermaid culture giving someone a seashell is the equal of marriage

you were walking on the beach during the night and spot a man on the water, stretching his arm to pick seashells, after a while he turned to swim away but you noticed he dropped one, a beautiful murex shell, and walked towards him, tapping his shoulder and offering him the seashell

when he turned to you, you finally noticed the fish-like features he had, such as fin-like ears, scales on the corners of his face and some parts of his body, he looked at you, then at the shell

"Oh my! How bold! Am i that pretty you asked me out of First sight?"

He smirks as he leans to grab the shell