What does the spiky sea creature called the sea urchin mainly feed on?

What does the spiky sea creature called the sea urchin mainly feed on?

سمندری ارچن نامی تیز سمندری مخلوق بنیادی طور پر کیا کھاتی ہے؟
Explanation

Sea urchins feed mainly on algae, so they are primarily herbivores, but can feed on sea cucumbers and a wide range of invertebrates, such as mussels, polychaetes, sponges, brittle stars, and crinoids, making them omnivores, consumers at a range of trophic levels.