My kid dug up a weird rock in our backyard and 3 professors later it turned out to be a 900 year old tool
Honestly I almost tossed it in the trash pile with the rest of the junk we cleared that Saturday. My 8 year old kept saying it looked like a knife, and after it sat on our kitchen counter for 6 days I finally emailed a photo to the local college. A grad student got back to me in 2 days and said it was a chert scraper, likely 800 to 1000 years old, probably used for hide work. Now my kid thinks he is an archaeologist and I have a plastic bin of rocks under my sink labeled do not throw away.
Did the professors tell you to keep it dry and out of sunlight? That chert will flake apart if it sits somewhere damp, so a plastic bin with a lid is actually a solid move. Just snap a photo of it now with a coin next to it for size, in case the kid loses it in a week.