Our shower is 1980's 'pseudo marble'. The floor has radial cracks around the drain. I want to tile the whole shower ie walls and floor to upgrade. I'd like to tile straight over the marble by first preparing it by sanding or some such. It is obviously best to remove the marble but I am worried as I don't know what's behind it or is it just 'glued' to the sheetrock and floor. It would be simpler to tile over it. Has anyone any experience in this please.