The Strange Green Ring Inside Your Hard Boiled Egg Is Freaking People Out—But The Real Reason It Appears May Surprise You

That greenish-gray ring isn’t mold or spoilage. It’s a harmless reaction between iron in the yolk and sulfur in the egg white caused by overcooking.

To avoid it, don’t overcook your eggs, and cool them immediately in ice water. The eggs are still safe to eat—the ring is just chemistry at work.