Look It's Bob! The Happy Water Cleaner for Spas or Pools.

For extra clarifying power, use Bob the super scum absorber. Using technology originally developed to clean up ocean oil spills, this floating foam collects water contaminants that create scum lines, cloudy water, and clogged filters, all with a smile on his face! To use, simply float on spa water surface. When Bob becomes saturated, simply rinse in fresh water and wring out (not in spa) to prolong the life of Bob.