SBS
I have been away from this forum for a while and have picked up this query a bit late.
Anyway I would think by the sound of it that the marble was at some stage 'polished' with a crystalizer and the swirls are from the steel wool used.
I run a stone restoration business and am vehemently against crystalizing marble - and the answer to your problem is to diamond hone then re-polish the floor using abrasive powders.