Authorities in Sydney have closed Coogee Beach and another popular beach following the discovery of hundreds of mysterious black spheres washing ashore. These objects, described as golf ball-sized black balls, have caused concern among beachgoers and prompted health warnings regarding possible contamination. After investigation, the mysterious debris has been identified, alleviating fears of a potential oil spill or environmental hazard. However, officials continue to urge the public to avoid the affected areas until further assessments are completed.