Un piccolo mistero in Oregon

I recently visited my half-brother Gerry and Gerry’s wife Tammy at their new home in Coos Bay, Oregon. Their home is lovely - reached by a short drive across a narrow land bridge that crosses part of the bay, it’s set on 2 acres with a small pine forest and beautiful, green grounds. They have an apple tree in their yard, which had un misterioso mecanismo underneath it:

What do you think it could be? Check by clicking the SOLUZIONE button