Just bought this today, wondering what it might be worth, not for weight, but antiquity. Can’t really find much on the internet about it, perhaps you fellows and ladies can help. I’m new by the way, nice to meet you all. 
Hi there and thanks for joining us. Your little Tiffany shell dish was, of course, made by Tiffany of New York and I’d just be guessing at the date - probably early to mid-20th century. Anything Tiffany is worth two or three times what a similar item from just about any other American sterling maker would fetch. I’d venture something in the range of $100. You may wish to follow the “completed auctions” on eBay for Tiffany silver and perhaps find a more exact value.
Regards,
Uncle Vic
That’s what I was thinking too, looked all around for it. Couldn’t find one that was stamped exactly as the one I have, but I figured it might be around the same price. Just took a lot of 14 that someone was selling and divided the combined price by 14. I figure buying one will be more expensive than a lot, and I found another one that was 2 of them and divided the lot in half and got around the same price. Thanks a bunch, I will definitely have more things for you guys to help me with soon 
Your “seashell thing” is normally called a butter shell, presumably because it may have been used to hold butter (in pats or curls) for use at the table. Some people think they are for salt, but if that were the case they would need a liner to protect the silver from the corrosive effects of the salt.