A friend just picked up a stash of molds in a package deal and asked me to help figure out what they were.
What struck me most was the method of storing the mold blocks. Whomever they came from had put a single mold block wrapped in VCI paper into a salsa jar along with a desiccant pack, put the lid on, and then labelled the lids.
I'd be a little leery about storing sharp cornered steel blocks in glass jars, but the airtight containers with VCI paper and desiccant isn't a bad long term storage idea.