u/BtwScyllaCharybdis

I recently unpacked some games I had in storage, and noticed this on some of the pieces.

These were kept in some cardboard boxes while I lived in one place for years (New England). We did have mold issues around the house. Later, when I moved, those boxes were wrapped in cling plastic and stored in a climate controlled storage facility for about 3-4 years. I only recently got them out and opened it up.

These are plastic pieces with some heavy paper/cardboard bottoms. It's only on a few pieces that were stored separately from the rest. This looks brownish and feels hard and rough to touch, so I really confused on what it is, but it looks like mold to me. It just doesn't look like any of the mold I ever saw around that house.