Plant: Tree burls.........

Burl is an outgrowth on some trees, where the tissue growth has gone awry...
some burls that I have come across during my hiking........
Birch...

California pepper...

Brazil pepper....

Eucalyptus.........

Coral tree.........

Pine......

A huge one..

A root burl of wild cherry....its a chaparral plant, so the burl serves to revive after a fire...

Not sure which tree......

A huge burl on a big-leaf maple in Olympic National park..

The bulged matter is often chopped off to carve articles......for table top, bowl, wall hanging, knife handle, vase, clock.........