I remember my late father having some cork sanding blocks maybe 50 years ago -- that he'd been given probably 30 years earlier! Back then, we kids thought cork was used because they didn't have the foams/plastics we had then or now. Guess that proves they knew something that worked well all along, and that "modern isn't always better".
...cork sanding blocks are used by luthiers among other craftsmen.
I'll admit I had to Google that word -- a Luthier is a maker of stringed instruments, based on the French word for "lute".