The Mermaid window was featured in the Prefect bathroom of Harry Potter and the Goblet of Fire. It sang a clue as to how to figure out the golden egg that Harry got from the previous trial.
I purchased this from a wonderful seller on Etsy: Magicbimbo. She has many great Harry Potter ornaments she makes and sells!
I’ve also purchased the Three Brothers ornament, the Azkaban Prisoner Plaque, the Fat Lady Portrait, the Mirror of Erised, and the Educational Decrees from her.