I agree with C-man on the types of shells he pointed out. Those are normally the 'best'. Do keep this in mind too BV, crud and crap is still going to need to be gotten out of the tank, and with enough shells in a tank, that can be a task in itself. Even though in the Lake some shellies (like mulites) are found in shell beds that can be meters deep, it's not feasable to do this in our home tanks.
I wouldn't think to much about shells till you find out what species your going to get. Multies like several shells per fish, while brevis normaly only use one per fish. Also I would avoid any shells that have really tight spirals as I've heard that some fish can become traped in them unable to get out.
I wouldn't think to much about shells till you find out what species your going to get. Multies like several shells per fish, while brevis normaly only use one per fish. Also I would avoid any shells that have really tight spirals as I've heard that some fish can become traped in them unable to get out.