Why is the marble in the hotel shower room comfortable to step on?

Generally used for shower room floor, either granite fire surface or marble grid surface. But according to your description, it is very comfortable to step on, which should not be these kinds, because the burnt granite is a bit Mao Mao, with first-class anti-slip effect but no good foot feeling. Marble grid, possible, but you didn't specify this grid, so I guess not.

Then there are two possibilities, either to brush granite with a steel brush after the fire, so that the surface is not so rough and the foot feels good, but the anti-skid effect will decrease. Or the antique surface technology of marble, achieve the effect of roughening by pickling, and then brush it again.