A Tennessee woman has discovered the rock she's used as a doorstop for 15 years is a 450-million-year-old fossil.
A local paper reports Betty LeMaster found the 10-pound rock when she was cleaning up her property.
She became curious about it while watching a TV program called "America Unearthed."
Alan Brown of Middle Tennessee State University says LeMaster's rock is fossilized coral.
He adds it's a lot older than a dinosaur bone.