Real sea urchin for sale. They were called "hedgehog of the sea" back in the day. Today they are an expensive delicacy in many parts of the world.
These creatures called echinoids or echinoderms have spines that help protect themselves from predators. The spines are removed and most are discarded. This leaves us with a rounded symmetrical beauty to display. Decorate your surroundings with sea urchins and shells.