Story in progress: "Shelf"

I started this piece of sf last summer, and as of this week it's exceeded 5,000 words. All I'm going to say is that it deals with humans forming a symbiosis with sea creatures on another planet, after these humans have forgotten the details--other than vague mythological references--of the world they came from... and much of the technology they originally had brought with them. The title refers to a continental shelf and the inhabited island that perches on its edge, at a ledge that forms a overhang over the drop-off. Many possibilities here--I just won't give away what ones appear in this story...