Most urchins are voracious algae grazers, but some species have an appetite for meat. Watch this time lapse video of an opportunistic urchin consuming a dead chromis. Public service announcement: Even herbivorous urchins can turn carnivorous when starved of algae, so make sure to feed your urchins if your tank is free of algae (lucky you!).
I'm a passionate aquarist of over 30 years, a coral reef lover, and the blog editor for Advanced Aquarist. While aquarium gadgets interest me, it's really livestock (especially fish) that captivates my attention.