Thanks for the advice!
I have a day set aside next week for some really delayed spring cleaning. (aka. mission "unearth the living room")
This was the only box they got into thank goodness. I had to store them outside for about 2 years. They were in an old grain bin for quite awhile so it could have been worse. (That place was sealed tight so the mice that got in were really talented.) About half of my stuff is still stored elsewhere, but most of the pony stuff is in good solid rubbermaid totes. The rest is safe and sound indoors with me.