Horseshoe Crabs - they're kind of cute, aren't they? It's best to find them dead on the beach or in an artificial form - especially because their blood contains amebocytes, which play a role similar to white blood cells, and medical firms harvest them, bleed them for their "blue blood" and
then return them to the sea. Plus, they're important to the ocean ecosystem.
(Design above by Marika Meyer)
Bronze Limule Sconce, here
Painted silver, from etsy here