The poop chute.
Pictured here, my adoring husband posing with the gross bottom. He promised me that this isn’t #2 – it’s toilet wax ring residue and assorted dirt that creeped underneath the toilet.
This step is important in toilet replacement because if you leave all that nasty gunk there, the new toilet won’t get a good seal around the hole… and I don’t have to tell you why that seal is crucial to your enjoyment of the new toilet. 😉