This is a replica of the fossils you dig up in Animal Crossing! It's made as a box, so the top piece is removable for you to store things in.
If you want to support my friend's design you can also help him by buying the 3D files here or tip the designer: https://www.myminifactory.com/object/3d-print-fossil-box-animal-crossing-new-horizons-113037 and check out his other awesome designs!