© Fletcher & Baylis via Wikimedia

Aaron LeBlanc was examining the teeth of a Komodo dragon—the world’s largest lizard—when he noticed a faint orange stain on their sharp tips. At first, this confused LeBlanc. He’s a paleontologist who studies fossilized dinosaur teeth. While he can’t observe living dinosaurs, he can study the teeth of their modern-day counterparts like giant lizards. It looked “like someone took an orange marker and painted the edges of the teeth,” he says.

LeBlanc and his team discovered that the teeth were orange because they were coated with a thin layer of the element iron. Komodo dragons are carnivores, or meat eaters. LeBlanc thinks the metal coating helps the lizards’ teeth stay sharp so they can tear through prey.