"Last week we came across these tiny sea urchin shells at a beach shop, thin and light as eggshells. What to do with them? Light them up with LEDs, of course! We've seen sea urchin lamps before, but they've always been made with large (i.e., sturdy) and colorful ones. In contrast, these tiny ones might be better to hang around christmas lights like little paper lanterns. Just a throwie sans magnet (Urchie?), tucked into the shell. Each one has a hole in the bottom large enough to fit a pretty good size LED, although not necessarily the battery as well."
Quick Project: LED-lit Sea Urchins from Evil Mad Scientist