This was originally posted in the form of a page that was recently deleted, so it's being mirrored here:
About fifteen years ago, I remember seeing a movie on TV. And one of the scenes marked me a lot when I was young. It was a scene where a child (about 7 years old) was in a bathroom. And in this bathroom, there was a tub with a closed curtain. The child starts counting to 10 and opens the curtain. And there, a humanoid "monster" with algae everywhere attacks it.