A rare whale that died in Irish waters in the summer had swallowed a chunk of plastic thought to have been the corner of a storage box.
Vets and wildlife staff who carried out a post-mortem examination on the surprise visitor made the disturbing discovery when examining the contents of the whale's digestive system.
They found the 10cm by 3cm piece of plastic lodged with fish bones partially blocking the whale's rectum.
The young Sowerby's beaked whale, which is normally found in the deep, cold waters of the North Atlantic, was spotted swimming in Wicklow Harbour in early July.
It died within a day, and the Irish Whale and Dolphin Group (IWDG) recovered its remains for examination at the Department of Agriculture's Backweston laboratory in Dublin.
The results, just released, were inconclusive.
Despite swallowing the plastic and having some skin lesions, cysts and some parasitic infections, the 4.3m-long male was otherwise healthy.
Dr Ferdia Marnell of the National Parks and Wildlife Service said examining the dead whale was still a worthwhile exercise. "Even if a definitive diagnosis is not reached, much can be ruled out and that is almost as valuable," he said.
"In addition to which, we have recovered very useful samples for life history, diet analysis, genetics and contaminant burden analysis, and have yet another example highlighting the extent of marine debris hazards to even these offshore species."
Simon Berrow, of the IWDG, said acoustic trauma - inner ear damage from shipping noise - was suspected in the growing number of otherwise unexplained whale strandings and deaths but the techniques to test for it were not available in Ireland.