Yes, I know the answer for this is "no, that's unrealistic and ridiculous," but magic in my world may just change that. You see, mermaids have the (super)natural ability to create and manipulate seashells (and pearls, but that's outside the scope of this question).
Now, I've decided that mermaids will use seashells as clothing (specifically seashell tops, but other seashell attire will exist too) in my setting, both for modesty and practical reasons (explained below), but that made me wonder. Could seashells even work as clothing?
I mean, realistically, there are only three justifications for seashell tops:
Magic-This should come as no surprise. Only with magic can seashells be conveniently molded to the wearer and given the strap (or straps) necessary to hold them in place.
Supply/Availability-Seashells are pretty easy to obtain in the ocean, and with their magic, mermaids can easily bend and even merge them to suit their needs. (Merging fuses two shells together into one seamless object, essentially turning four small shells into one big shell.) Generally speaking, humanity works not just with what is there but with what is easiest to work with, and this makes seashells a prime candidate for mermaid clothing material.
Protection-I believe it goes without saying that the female chest is a vulnerability and must be protected. Which would be better at that, specially made seashells or seaweed? Yeah, I thought so.
However, just because I came up with three reasons to justify seashell tops (or seashell clothing in general) doesn't mean they're actually viable. Perhaps they just can't be made comfortable enough, or maybe seashells have some irredeemable flaw that would prevent them being used in this way. So my question is, Are Seashell Tops Viable Clothing For Mermaids?
The best answer will account for the variables that determine the desirability, usefulness, and popularity of clothing, then explain why seashells pass or fall as a viable clothing material. These variables are supply, workability, comfort, and cosmetic potential (as fashion will be important to mermaids, they'll want something capable of as many different colors and designs as possible).
The best answer will also contrast seashells to other options mermaids have for clothing to see how they compare. As far as I can tell, these options are seaweed, marine animal hide, sponges, sea stars, sea anemones (decorator and boxer crabs do it, so why not mermaids?), and maybe even fishbones. Rubber was mentioned in this question, but I'm not actually sure how feasible that is, and while I am asking about seashells in particular, I am also willing to accept a better alternative as long as its pros and cons are explained alongside that of shells.