Ok so my husband wanted to put our 4 month old baby on a terrazzo floor to play on his activity mat which has barely any padding. Those of you who know how hard a terrazzo floor is please tell me do you think this is safe for a baby to lay their head on/practice tummy time (my baby lifts his head then drops it back down on whatever surface he's on which has always been the cushion of our bed) He thinks it's just fine and I'm just looking at him in shock right now...