CHRIS HUBBUCH Wildlife officials are asking aquarium owners to destroy their âmoss ballsâ after invasive zebra mussels were found on some of the ornamental plants. The U.S. Geological Survey warned Monday that the destructive shellfish have been found in pet stores in at least 21 states including Wisconsin. âThe issue is that somebody who purchased the moss ball and then disposed of them could end up introducing zebra mussels into an environment where they werenât present before,â said Wesley Daniel, the USGS biologist who discovered the problem. âWeâve been working with many agencies on boat inspections and gear inspections, but this was not a pathway weâd been aware of until now.â