I've had one for over a year and he is still in the same shell. I never thought to offer him another cone shell. I'll have to find one for him to see if he is ready for an upgrade.
this is kind of up in the air with is it ok or not ok however...the only place I can get cone shells around here is at the dollar store...I am not sure if I should do that...I really wish I could...does anyone know if it is ok?
My halloween hermit is friendly and showed me his body and back end. These guys have evolved/adjusted for cone shells as they are super flat. I put in 2 extra cone shells for him among the other hermit shells and he was only interested in the cone shells (but he didn't switch as I didn't get any big enough). Luckily a LFS sells cone snails and sometimes he gets empty shells that I can buy.
The halloween and blue knuckle hermits I've had seem to molt and retain the same shell. I will see them camped out in a acro or rock and then see their old body. Then a day or two later they are out roaming the tank again. They are in bigger shells and probably have plenty of room for the future. JP
Your LFS should have those shells lying around on their tank bottoms from turbos that didn't make it. We have had many varieties of hermits and each has a preference for the type of shell found locally where they are from.