I found a chunk of wood on the beach at Martha's Vineyard, about 18" X 6" X 6". It was so chewed up I couldn't begin to identify it. It was very heavy, but might have just been waterlogged, I was interested. I lugged it home, dried it out a bit, and cut it open.
To my surprise, it was a piece of old growth English White Oak which, I read, is called brown oak after a fungus attacks the tree, turns the wood brown, and eventually kills the tree. It is a very hard wood, and apparently very resistant to anything that chews on wood. The piece above is about 3/16" thick and marine borers have only had very limited success in getting that deep into the piece, even in the end grain. A most remarkable wood.