Odd ‘clam shell’ growths

[evo]

I’m finding growths like this more and more commonly. Frequently found on bigleaf maple, but noting them on other species like this Doug fir limb.
Not quite a callus, and also not quite like a burl.
I’ll frequently dissect them to see if I can find out anything.

A bigleaf had some damage removing the bark on the upper side of the limb, and a few torn fibers on the sapwood. A very small injury of little concern. The growth started radially from the side. It will take digging to see if I have any photos.

I might have gotten lucky with this lateral cross section exposing a pitch filled tunnel vertically going straight into the limb.

Anyone come across this type of growth? The pattern tends to start at one point and radiates outward spreading, not unlike a G. tugsa fruiting body. The ‘root’ is on the tree side of the removed limb, and nearly always on the top.
@KTSmith

 

[KTSmith]

Thanks for the longitudinal view along the radius. That tells me "yep, the unusual growth is wood tissue." Without any other info, I'd go with "crown gall" caused by Agrobacterium tumefaciens. Lots online on that one....but may not be too much help as to "why".