Hello! My name is Daisy, and I am a sea urchin - a purple sea urchin to be exact! Scientists sometimes call me Strongylocentrotus purpuratus, but I really do prefer Daisy. I'm about 3 inches across, and you might say I look like a pin cushion. That's because I'm made up of a round inner shell, called a "test," which is covered in purple spines. My spines are attached by a ball and socket joint, similar to your shoulder. Look at that! Even though I am an invertebrate, meaning I have no spine, we still have something in common! At least you're not covered in spines. Can you imagine trying to go to school covered in big purple spines?
I love my spines, though. They protect me from predators and help me to catch food, which is normally green or brown algae. I am also covered in tiny tube feet, which are exactly what they sound like: tubes that extend out and allow me to move around like your feet do for you. Unlike you, I also breathe through my tube feet, so I'm glad I don't have to wear socks and shoes!