It suggests it was buried for a purpose. It was buried as an offering.

The mouth of the Miami River would have been a preferred place to be if you were a prehistoric hunter and gatherer.

If that's exactly what the creators intended, who can say, but it certainly doesn't take a lot of imagination to see that it's eye-shaped.

I was really struck by the symmetry of the circle. It's absolutely, at least to the eye, absolutely perfectly circular.