[Nagisa shrugs, turning the shirt in his hands.]

No, not really! I mean, humans leave these on the beach all the time...you haven't really been on the beach before I guess, have you?

[He's got the physiology for it; Rin, however, can't actually leave the water like he can. He probably hasn't seen very many artifacts like this one, ones that wouldn't really make it that far into the ocean.]