Be careful when exchanging your shells for proof of myths, make sure you have enough room in your bag. I had a full bag went to exchange 350 shells got a message from the npc that said my bag was full and items could not be exchanged, but it took my 350 shells and i didnt get any items in queue like you normally would when your bag is full. I sent a ticket but we all know how that works, so just make sure you have enough bag space before exchanging. Oh i didn't get the 20 simple hammers or 25 mems either.