A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2020 Jul 17, 22:28 -0700
It's possible that it's centuries old, but I would bet it's a modern replica, maybe as young as ten years. There have been many replicas produced. I'm also a little suspicious of the photo... "Oh look at this ancient treasure I just found on the beach! Before I pick it up and examine it, I'll take a photo of it in this nice clean sand!" Heh.
Here's a copy of the image from the original post for reference.