Pacific purple sea urchins are easily identifiable on the ocean floor because of their distinctive purple color. Also, you can find them in our Cute Sea Urchins cursor pack. They are covered in pincers, tube feet, and purple spines that move via ball-and-socket joints, using these spines to grab food and protect themselves from predators. You could call sea urchins the porcupines of the sea. By the way, the pin cushion appearance extends from a round inner shell, called a test.