New York's American Museum of Natural History has an intriguing proposition: Bring in anything you have and don't know what it is, and scientists will try to identify it.
Saturday is what the museum calls its annual "Identification Day" devoted to helping people break the mystery of their specimens such as shells, rocks, insects, feathers and bones and more.
The explorations will take place in the Theodore Roosevelt Memorial Hall, named after the U.S. president with a passion for natural history.
Items identified in previous years have included a whale jawbone, a fossilized giraffe vertebra and a 5,000-year-old stone spear-point from Morocco.
Visitors are also invited to explore rarely seen objects from the museum's collections.