The purple sea urchin I’m holding doesn’t look like an environmental terrorist—more like a domed pincushion bristling with needle-sharp spikes. I can’t look this echinoderm (pronounced ee-KINE-o-derm), a cousin of sea stars and sea cucumbers,  in the eye. It doesn’t have any.  Nor does it have a brain, heart, backbone, or blood.  Yet urchins, among the most ancient animals, date back 450 million years and inhabit every ocean on earth.