In 1990, I had a very large birch burl sawn into 3 and 4-inch slabs. Most of it was turned in the next few years. But I left one slab outside under cover. Earlier this year, I cut that slab up for bowl blanks and found it had been thoroughly infested with small beetle larvae. This makes for some very unusual pieces. I try to turn most of these with thin walls for 2 reasons. First, this enables me to find any remaining larvae and deal with them. Second, I clean out as much of the worm holes as possible with a pick and compressed air, leaving a naturally textured surface. Most of the time, I don't apply a finish to these pieces. I have found from experience that unfinished wormy bowls just look and feel better than the finished ones. This bowl is about 5 inches in diameter and 1/4 inch thick walls.