I need help with Science!!?

I have a really stupid worksheet in science that's based on the movie Finding Nemo. The one question I haven't been able to answer is this: Describe a mutualistic relationship between two species that is shown in Finding Nemo. If anyone can help and give me a few ideas that would be great!! Oh and does anyone know if and how a sea anemone benefits during it's interactions with a clown fish?? That would really help!!