CHICAGO — Wondering if that rock you found recently is actually a fossil? Or maybe you have questions about the unique leaf you found outside? Let the experts at Chicago’s Field Museum answer all of your questions during its annual ID Day.

During the annual event, guests have the chance to bring in items from the natural world and have a scientist at the museum answer questions about them and do their best to identify them.

According to the museum, guests are allowed to bring in clean & dry bones, fossils, rocks, meteorites, seashells, artifacts, and photographs of mammals, birds, reptiles, fish and insects for identification. The museum asks guests not to bring in live animals.

The event is set to take place from 10 a.m. to 2 p.m. on Saturday, September 9, a day when admission to the museum is free for Illinois residents. The Field Museum is located at 1400 South Lake Shore Drive in Chicago’s Museum Campus.

Visit the Field Museum’s website for more information on the event or to purchase tickets.