Could Ben be immortal? I've been thinking about this for a while now. With the exception of Ben, every form in the Omnitrix is at its physical peak, and is broken down into energy and stored as neccessary. Obviously Ben ages since he doesn't stay in alien form constantly, but if he did I think he could arguably be biologically immortal. If he stayed in one form long enough I think he'd start succumbing to their natural biological processes like aging, needing to eat, and use the bathroom. But if he did, all he'd need to do is switch to any other form to avoid that.