We just learned about the Wolverine.
When you look at a turtle's shell and see the lines marking out different shapes on it's back or belly, those areas are called scutes
(from: wikipedia - turtle shell)
The scutes are like scales on a snake, and each scute has a name for where it is on the shell, like cervical, vertebral or marginal.
The scutes are made of keratin, the same as a rhino horns, whale baleen plates and our fingernails and hair!