I also added some plant life by the sea turtle appliqued down. The plant was created with pink/purple varigated EdMar threads in super long cast-on stitch...that twisted nicely. On either side is a piece of DMC Color Infusions Memory Thread in dark olive green. This is actually not thread...but super thin wire, coated and wrapped in thread. I wrapped a piece about two foot long around a large doll needle to get the coils...and then couched it down. The base of the plant was covered with a snippet of lace for another plant illusion.
Lastly, here is a wire and seed bead fish. It was created and then couched into place. The body is thin and flexible beading wire. The fins were created with a little thicker wire, bend into shape, and then all was wired together.
Hope these photos give you lot's of stitching and embellishing ideas for your own Under the Sea kind of block!