interesting sea urchin facts

Sea urchins are echinoderms, meaning spiny skin.
Sea urchins have spikes all over.
Sea urchins are immortal.
Sea urchins have five-fold symmetry.
Sea urchins are named after hedgehogs, which were called urchins.

http://findarticles.com/p/articles/mi_qn4158/is_20031125/ai_n12722815