Apparently Mr Clean Magic Erasers are just this stuff called Melamine Foam. You can buy it in bulk on Amazon for WAY less than Mr Clean brand name! 30 sponges for $6.00! Melamine foam - Wikipedia.
Erasing Stains with Melamine Foam - How do magic erasers get rid of stains? | HowStuffWorks
* HowStuffWorks "How do magic erasers get rid of stains?" [melamine foam erasers]
Buy melamine foam instead of Magic Erasers. | 46 Penny-Pinching Ways To Save A Lot Of Money This Year
FR melamine foam acoustic foam for wall and ceiling decoration
Did you know that Mr. Clean Erasers are just Melamine Foam you can buy from other places for much cheaper? WOW!
Melamine foam (Mr. Clean Magic Eraser)