Winter Sky

Acorn Mystery

 When I did an image search of just these large seed pods I got results which showed a variety of possibilities for identification including sycamores and oaks.  A search using an image of the contained component yielded no better results.

I went back to the park to take a better look and saw that a number of the pods had opened to reveal what appears to be a cap on an acorn.

Another image search seemed to narrow the choice to some kind of oak, possibly a Bur Oak.  I believe there are around five hundred types of oaks, so I'll await the judgment of someone with real expertise on the subject.

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( I am told by a trusted source that the correct answer is "Bur Oak".)