Reddit users call the hole between the seat and central ridge the Pit of Doom. We quote one of the top comments there: “If I had a nickel for every nickel I’ve lost down there, I’d have zero nickels, because I’d lose them all down there.” People often lose wallets and cell phones in that hole and it is probably the first place to look for the missing stuff. Luckily there is a thing called Dropstop, which you can buy and install to cover the hole once for all.