I have seen sea urchin type accessories popping up from my brass lighting, to decorative accessories for a coffee table or book shelf. Here are some of my fave images using the urchin shape!
Assorted brass urchins from Furbish
Assorted gold sea urchins for table or wall from Number Four Eleven
Urchin DIY-styrofoam balls, wooden sticks and gold spray paint from Make Them Wonder blog
The Real Deal- A sea urchin with it's spikes!