Sea balls (also known as Aegagropila or Pillae marinae) are tightly packed balls of fibrous marine material, recorded from the seashore. They vary in size but are generally up to 7 centimetres (2.8 in) in size. In Edgartown, Massachusetts a longish sea ball around 45 centimetres (18 in) in diameter has been found.[citation needed] Others have been reported at Dingle Bay in Ireland [1] and at Valencia, Spain. They may occur in hundreds and are composed of plant material, in majority seagrass rhizome netting torn out by water movement.[citation needed]
In recent years they have been shown to contain more and more plastic marine debris and even microplastics.[2]