The oldest crocus

When I bought my house, there was a, well, shack next door which I eventually bought and demolished. The people who owned it had planted various flowers here and there but most were destroyed when the place was torn down. Several croci remained and bloomed faithfully every spring. When the barn was built and the yard bulldozed, I assumed the old bulbs were gone. After all they had been around for more than 40 years. Last spring I was very happy when the two purple flowers appeared. Meanwhile I had the area scraped for large rocks and debris last fall and assumed that would do the bulbs in. Obviously it didn't and I'm very happy! The other one is 10 feet or so from this. I have planted snow croci but never the large ones so I have reason to believe that these are offspring of the original ones if not that old themselves. They are not the sort that birds and animals propagate.