My son found this for me, freshly cut up in Bellingham, Washington. It was the largest single piece I’ve ever turned, and the largest I could mount on the lathe by myself. The knots are natural - it’s a characteristic of the species that they grow in a ring like this. The blue-gray streaking is the product of fungus getting started - the wood is dry, now, so that process is arrested. Finished with oil/varnish, buffed with wax.