They get caught in trees (hence the epithet "Witches' Knickers"), take hundreds of years to decompose and push up demand for oil, used to make plastics.

它们挂在枝头（由此而得“巫婆的灯笼裤”之名），需要数百年才能分解，它们助长石油需求，正是石油用于制造塑料。