I have an older home with two of the original toilets that work fine. I'd like to change the seats however for obvious reasons. I do not recognize the nuts that holds on the seat, they have a look almost like a castle nut. Do they look familiar to anyone and would it require a special tool to remove them? I have sprayed them multiple times with WD-40, Kroil, and other solutions to loosen them up as they are badly rusted. However, I'm reluctant to just go after them with a pipe wrench or adjustable wrench for fear of cracking the porcelain. Thanks for the help!