Crabs! French knots and detached chain stitch.
We were given a 'bonus' stitch, over at StitchinFingers, a stitch one of our group had done this week. She used the simple straight stitch to create a feather-ie look. I tried to use my version as something grassy. I added it to a threaded buttonhole stitch.
I started the french knots in another color thread, hoping to come up with some kelp-ish, but as soon as I saw the shape of the chain stitch I had just made, I envisioned a crab. So out came the first bunch of knots, that were knot kelp-ish at all, and in went the crabs in another color.