We had a round marble 'cheese board' which I never used for cheese
because I prefer wood (it's kinder to knives). I put it in the oven
to bake a pizza and it worked very well so I reminded Spouse of the
piece of 3/4" thick white marble propped up in the garden and he cut
a piece to fit my oven. I've used both of them so much as baking
stones that they've turned deep brown. They don't need to be greased
or corn-mealed, when the stones are hot the shaped dough just goes
straight on them.
I expected them to crack but they haven't and if anything is spilled
on them they're easily removed and cleaned. They've also been dropped
and otherwise mistreated, they seem to be impervious to any harm.
Mary