Sea form is what you get when dissolved organic matter mixes with water (by way of wind and wave), and gets washed up on the beach.
What did this image teach me?
I have learned more about the creation of sea foam than I will probably ever need to know. For example, in January this year a small Spanish town was inundated with sea foam. It ran through the streets like a river, despite the fact that the town was over an hour and half away from the coast!