This mysterious object was found in the Maine woods. What do you think it is?

BANGOR DAILY NEWS • April 10, 2020

Tony Valcourt of Hampden was hiking with his dog, MacGyver, on April 6, when he came across an unusual sight. Clinging to the trunk of a young tree was what appeared to be a sac or nest built of natural materials, and it was about the size of a baseball. What do you think it is?