Given that the shell is directly connected to the spinal column, I imagine this would be a lot more trouble than it's worth.Has anyone ever wondered if Tortles keep the shells of deceased tortles amd use them as armor (or even shelters)?
On the other claw, yeah this makes sense. Though by 5e rules this wouldn't help your ac unless it was magical (or homebrew).maybe Lizardmen cure the hides of their ancestors and wear them as cloaks?
Or to become a Living Construct like the Warforged.more armour is good become the living tank we always were meant to be

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.