Oh! A word I've heard of! A couple of years ago at an art fair, I bought a...carving, I guess...made from madrone. It came from Oregon (hi, Sweet Geoff!). It's amazing--it looks as though separate thin layers of warped wood have been stacked, then glued together here and there. But it looks like it just grew that way! The inside is hollowed out, and is smooth, so that it somewhat resembles a Cat-in-the-Hat hat. Could it be a knothole, or something, does anyone know? I can't imagine a big tree being able to withstand even light winds, if the layers really grow far apart like that.