if it’s what I’m thinking of, those are called Burls if you’re murrican or Burrs if you’re from pretty much literally anywhere else
It’s less of a disease in itself and more like a sign of a disease. Usually fungal infections fuck up the tree growth and cause them
People actually steal them sometimes because some of them are super valuable. They make really cool looking carved stuff and are really dense.
what the fuck. they just chop the ass right off a tree and sell it to the tree ass black market. that’s brutal