Why, such a tumorous growth? is that a special case? again are the colours original or adjusted?
Regards
They are fairly common on some trees and can be caused by various kinds of stress. See https://en.wikipedia.org/wiki/Burl.Why, such a tumorous growth? is that a special case?
They can produce very interesting patterns in carved wood objects, such as bowls. You can see this online. Search with the word "burl", which is common on this side of the pond and is more specific in meaning than "burr". Search for something like "wood carve burl" without the quotes and click on images.