Maya
Aquarium Advice FINatic
No they aren't bad. YOU don't like them and that's fine. Your personal decision on what goes and stays in your personal tank. But they aren't bad. They are good for your tank. They serve the same function as starfish, shrimp and snails. They are common cleaners who come with almost all live rock. If you aren't going to want anything that stings, bites or is toxic you'll need to cross off all anemones, almost all corals, urchins, and more than 50% of all saltwater fish.