What does the sea urchin eat?
Sea urchins mainly eat algae and coral. However, they also are known to sometimes feed on decomposing matter such as dead fish.
I think a sea anenome and a sea urchin can live together because i have a little aquarium and there is a sea urchin and and a sea anenome (if that's how you spell it) living in there and they were perfectly fine. BUT if you have a sea urchin do not have any crabs in there, because my sea urchin killed one, and almost killed another one by taking its claw off. :(
Sea urchins have poisonous spikes so sea life find it very hard to eat them. But otters use rocks to crack them open and eat them also humans will gut the sea urchin and eat there insides You can find out by asking other people like your teacher, parents, friends, and brothers or sisters if you don't think this answer is right. the answer is otters, people, and heron.