Yesterday my wife and I discovered a spider who thought itself clever. This story is going to require a little explaining about how ceramic is made.
Clay shrinks when it is fired(cooked) in a kiln and turned into ceramic. Holes are required to give any trapped air a place to escape. If you don't do this, the heated and trapped air will cause the "project" to explode.
Back to the story
The lid to your toilet is a huge ceramic slab...
This clever little spider decided to set up shop in one of these holes in our toilet. I would never be able to ... relax... knowing a spider is lying in wait.
I shout: "Nice little home you have there... too bad it is your TOMB!" and we seal up the hole!