What is this brown seed pod found under a large evergreen tree?

Question

Please help me to identify the seed. I was thinking it was a sweetgum tree of some kind, but then it is a bit different, so I remain in doubts. I attach the image of the pod and the tree under which it was found in great quantity. It is taken in South Florida. I would appreciate any input.

Answer 1

This is Casuarina equisetifolia or "Australian Pine". It's an invasive species from Australia.

See Florida Fish and Wildlife Conservation Commission.

Here's a nice anecdote by someone else who was flummoxed by its identity.