Knobby Red StarfishKnobby Red Starfish Also referred to as the "Red Thorny Sea Star" The Knobby Red Starfish is found in the Caribbean Ocean, and is not considered to be reef safe. They will eat algae while they are small. However, as they grow older and larger, they will begin eating fellow tank mates such as starfish, sponges, soft corals, and other invertebrates. This species cannot handle air exposure, and should be managed with care.