Well, it's getting very interesting as the kelp dries and pulls back, exposing the stitching. This is a bigger piece - stitching two pieces of kelp together with red silk.
You can see on the smaller one how the kelp is shrinking as it dries - this is quite hard and leathery but the stitching still has integrity and hasn't torn the kelp at all.
One of the surprising characteristics of the wet kelp is how it behaves like the self-healing cutting mats you use for quilting or paper work. If you poke the needle in the wrong place the hole immediately heals and closes up as the needle is withdrawn.