Here we’re a year later and the mattress is developing “mold like” spots. 
I thought it was just something my 10 yr old daughter spilled on the bed, however my kids aren’t allowed to bring food or drinks into their bedrooms only a water bottle. I’ve purchased a water resistant cover for the mattress so it won’t happen again but their is another spot. So now I know it’s not from her. As much I want to love this mattress I must say it is nowhere near medium firm! It is extra firm. It’s like putting a blanket on the floor and then laying down on it. Very disappointed (