When trouble looms, the fish-scale geckos of Madagascar resort to what might seem like an extreme form of self-defense — tearing out of their own skin. Now, new research shows the geckos’ skin contains a hidden strength: bony deposits known as osteoderms, the same material that makes up the tough scales and plates of crocodilians and armadillos. But the presence of osteoderms in fish-scale geckos raises a herpetological mystery: If they have armor, why do they discard it?