Can anyone ID these two odd hermit crab shells?

[wodesorel]

I apologize for not knowing more about them, but I've been searching for an ID on these two shells for around 3 years now and I've never been able to able to find a match on either of them. (I've even searched through the online catalogs plate by plate!) They are the most popular shells I have for very small hermit crabs, and I would love to know what they are and where they come from in the hopes to be able to find a few more!

The brown and white one came from a friend who wasn't sure where she got it. I don't have a history on it at all. It used to have a very nice sheen on it.

The grey one I'm assuming came from Central to South America, Pacific Ocean. It was found on a very small coenobita compressus at the pet store, and that hermit crab species generally sticks with the shell it was wearing when it was collected. However, it could have picked the shell up at the store or been given the shell after collection, so it's impossible to say for sure where it came from.

Both shells are approximately an inch and half long from tip to tip. They are both in rough shape as they've been in near continuous for three straight years. (Yes, there are currently very tiny hermit crabs in both shells, including in the photos.)

I can probably get more photos of different angles if it would be helpful for an ID, however it might take a little time as I believe both hermit crabs are underground and molting right now.

Thank you for any help you can provide!