Behind Jill in a couple pictures you can also see a trait of wood I learned recently. In the picture where she's on a piece of wood, you can see what's called an open grain. Usually this occurs in soft woods but that piece is white oak. Though the stuff is very dense, it still has those hollow grains. So too does the ash that we used so much of in the house. Closed gain woods can attain a very smooth finish much easier. Some people will cover a whole area with wood filler before they sand so that they can get the closed grain like finish.
It goes to show how abundant, and ubiquitous spiders are. They are in your home right now, but don't worry, that rumor that you eat them in your sleep constantly is a rumor spread by some arsehole.