I'm not referring to chemical substances as poisons and whatnot, neither to heavily treated stuff like leather.

This question popped up in my mind when I was watching some footage with some sea turtles, and I thought to myself that their shells were remarkably similar to heater shields. I never touched the shell of a turtle nor do I know how hard and heavy they would be, but now I'm really curious about them being actually used or not as shields by humans.

I looked for information on the subject, but I didn't found anything worth of note, so I thought I might ask here if anyone knows anything about this. And also if there are any other examples besides the one I'm asking about.

Thanks in advance for you time.