I am more or less an expert on trees with over 20 years of field experience..
IMO.. That tree looks to have suffered from mechanical damage, maybe an ATV ran into it some time ago (years)?
It also could have been a co-dominant (two trunks) tree, and one side of it died, with the living half still trying to compartmentalize the area where the damage occurred...
It could be a malformed burl as well, caused by a burrowing insect larva...
Looks to be a red elm from here....
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