What seems amazing is that it isn’t covered in more sand and sediment. It would take such a small thickness of covering to hide it from view forever.
It could be U shaped and not just a flat panel. Also, I assume the ceramic tiles have a very low coefficient of friction, so if it was stuck at any kind of small angle, the sediment might easily get carried off.
I got to hold a sample of one of the white tiles a long time ago. I don't know if it was identical to the flown versions, but it was anything but smooth.
I remember being able to feel and see individual silica fibers. It was very much a 3d surface.
I believe they are rather similar to the fire tiles you can get to line the inside of a blacksmith's furnace. They are quite light, but also very fragile.
I wonder if it could have gone through cycles of buried/uncovered? I don't know anything about the waters off Florida other than they experience periodic hurricane events.
Very likely. I am in the west coast of Florida, and storms can really shift things around quite a bit. Passages between some of the small islands can open or close after a decent storm. Sandbars come and go, etc.
The waters tend to be a little deeper on the east coast, which would tend to lessen the effects of large shifts, but over a timespan of nearly 40 years it is very likely the piece had been covered over at some point.