This phenomena is known as efflorescence or salt sedimentation on surface of marble. It happens when there is dampness below the marble. This dampness doesn’t have an outlet to dry so it seeps up through the marble and comes to the surface of the stone. Upon drying it leaves white patches which can become rough.
This problem occurs in flooring which is surrounded by garden on all sides or by a water body and adequate water proofing is not done to protect marble.
When clients come to us with such issues, some people have the impression that polishing the marble with diamond grits will cut the white spots and solve the problem. Unfortunately, this is not the solution. Temporarily the marble will look good. But eventually if the source problem is not resolved, the dampness will once again come through the marble and dry on the surface.
We have temporary solutions such as diamond polish with epoxy to create a film over the marble or the application of sealers meant to protect against efflorescence. However, it is likely that the efflorescence will come up again. You may ask how long will these solutions last for. It all depends on the level of moisture in the stone.