Hermit crab not switching shell in 3+ years

[Bodog]

I have had my hermit crab for a little over three years now and not once has he changed shells. I have gotten him so many different shells in different sizes but he has just never changed. I’ve heard about calcium sand being able to “cement” crabs in and I used to use it but he is not and never really has shown signs of any problems other than not switching shells. This is the only thing I could come up with so does anyone know what might be going on or what to do about it?

[wodesorel]

No, calcium sand hardens to them, which prevents them from moving around normally, or shedding when molting. You'd have known a long time ago if it was causing problems.

Once crabs reach a certain size and find a shell they like, they have no reason to change. Shells offer protection, but at a trade-off of taking energy to carry around, and to modify to comfortable. There's no advantage to changing out of something that is good. I've had some crabs in the same shell for at least 5 years, some I suspect more like 10 though it's easy to lose track of who is wearing what. They'll often wear holes in the bottoms before reluctantly changing.