Thank you, Kamnaskires, for the proper orientation, and thanks robinjojo for your informative reply.
I assume they are not very valuable, like maybe about $20 each given their condition, but I'm trying my best to locate their owner, because I suspect they might have been lost by a child bringing a souvenir to school for show-and-tell, and I feel sad to think they might be missing them (or worse, in trouble for losing them).