Here is a craft we made to go along with Eric Carle's book Mister Seahorse.
First, I drew an outline of a seahorse and cut it out. I used this as a template.
I traced my template onto cardstock. For one ornament, you need two seahorses (cut out back to back because the backs will be glued together).
When the seahorses were dry, I threaded a piece of knotting cord through the hole and knotted it.
Finally, we hung our seahorse on our Christmas tree. :)