Although I don't even recall the last time I've used an eraser, let alone needed one, the Pebble Eraser seems like a good one to have on hand. Also, just because I haven't needed one, doesn't mean it's not used profusely in other industries. I just happen to write predominantly on my laptop nowadays.
Designed by Ching-Chan Wang and Ya-Ting Yang, the Pebble Eraser is not only interesting to look at, its look serves a purpose. As it erodes, it maintains its sharp edges, which proves useful when erasing certain marks.