WElcome to the site.
I think that's some sort of outdoor candlebox, for citronella etc. Probably not that old based on the cotter pin hinge. Still a good find
It's always good to have more support. Some of the shelves I've seen were basically screwed to drywall and not studs. Then the shelves get loaded up over time. And then it all goes crash. Yours looks fairly sturdy for the load
Top left looks like a Marble King (I was hoping it was a Peltier, hard to say from the pics) If it's Peltier it would have been marketed under the Rainbo brand. And the dark one is a Master Marble. Thanks
Bottom right is a Peltier NLR (National Line Rainbo). Blue and red in the middle also looks Pelt, but Alley also had a similar color combo. A couple catseyes, a couple clays. Nice marbles. Clay is probably turn of the century. Peltier I'd put in the 30's. the other swirls and cateyes are...
Surprising how well they cleaned up. I hate to think how many I left back in the dunes since they were so "rusty" . Citric acid is what gave you those results?