As volunteers who spend every Sunday removing garbage from canals crisscrossing the Dutch city of Leiden, Liselotte Rambonnet and Auke-Florian Hiemstra have seen more than their fair share of litter.

But even the ecology Ph.D. students’ vast experience with urban detritus didn’t prepare them for what they stumbled across last August.

A finger-size perch had gotten trapped in the thumb of a disposable medical glove, where it died.

The discovery—the first recorded observation of its kind—concerned Rambonnet and Hiemstra, who immediately began scouring the internet for more reports of wildlife harmed or killed by gloves, masks, and other littered personal protective equipment (PPE) used during the coronavirus pandemic. These