Peace Lily. They do this when they experience something new, e. g. a draft, too dry, too wet. Just chop it (the yellow leaft) off at the base. Best to water by standing in a bucket for half an hour to let it absorb what it wants. Rain water is great, especially if you let it warm to room temperature before immersing. My friend bought me one 30 years ago and periodically I split and pot on.