Can someone explain what a foam "Magic" eraser is?

I gave my partner a foam eraser and told her to wet it & use it to wipe out some dirty marks.<br><br>She thought it was a cleaning wipe and was like "Oh, nice!"<br><br>Turns out they just didn't exist outside of the US.<br><br>For those like her, it's a foam block of super fine sand. I'm considering calling them magic sponges.