CHICAGO (CBS) -- Attention collectors, scientists, and anyone who gets geeked out by old mysteries: A fan favorite at the Field Museum is returning after a four-year break.
It's ID Day at the Field Museum.
You bring in your collections of rocks, fossils, and animal photos, and scientists identify them for you.
Historically, folks have brought items that date back to the dinosaurs. You're asked not to bring anything alive or even recently alive.
ID Day is this Saturday, and it's also a free day for Illinois residents.
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