I seldom disagree with Doresy on things but this time I will. The plain plastic pot scrubbers work better than the bioballs because they have a much larger surface area in a given volume than the bioballs or almost any other biomedia. The price difference is not much, as he said. To me the difference is in performance. I doubt anyone could sell bioballs that looked like pot scrubbers because people would take one look and say "hey I can get those things a lot cheaper". I am guessing that is why they don't look like the scrubbers.