hermit shells

I really want to buy new hermit crabs of all different sizes and colors but I don't know how to tell if a shell is too big or too small. I used to have a few hermit crabs but they would kill each other to get the biggest shell. Now I only have one. I'd really love more Hermit crabs but I want...

So I'm working on my extra hermit shell pile, and I came accross a pile of sea shells I think came from a home decor section. The ones you can buy for plants or a bowl just to look nice. Are they safe to use for my hermits? How should/can I clean them before they go in the tank?

doess anyone have any spare hermit shells that they would want to sell? im looking for some smaller ones for my red tip hermits.

This is my first experience with sw (good thing I'm only riding shotgun) It seems that we have a "special" hermit: Couldn't catch any of them swapping shells till we put in more extras and one of the blue legs went from 1 to another, back to the 1st, then back AGAIN to the 2nd, all in the space...