If you are so inclined, please take a look here:
What's the purpose of that marble base under the toilet?
This is in a bathroom that was added on to our house I'm guessing in
the 1950's. I'm just curious why its there at all. It looks like it
was installed when the bathroom was built, so I don't think there was a
need to adjust the floor height to the waste flange height or anything
We're gutting and redoing the bathroom (don't you just love those
plastic tiles on the wall?), and my wife wants to keep that marble
base. New floor will probably be 1 inch hexagon tiles, and it seems to
me it will just be extra work for the tile guy to tile around that base
rather than just tiling all the way up to the flange. All plumbing
will be new, including a new flange set in the floor, so the new flange
can be set to whatever height is necessary for the tile thickness.