The Rainbow Pincushion Urchin is round with very short spines and grows only up to 3 inches in diameter. The Rainbow Pincushion Urchin is a grazer that roams around the tank searching for food and alga on the substrate and rockwork. Hence lots of live rock work is required in an aquarium. The Rainbow Pincushion Urchin is not really considered reef-safe, as it may damage or nip over the delicate corals by crawling over them. The Rainbow Pincushion Urchin can also be fed by introducing attached algae sheets to a piece of rock with a clip or rubber band, if there is less algal growth in the aquarium. Its mouth is used to scrape algae from the rockwork. Apart from this, the Rainbow Pincushion Urchin can also be provided with dried seaweed for its good health. If its spines are poked in your hand while handling, it may inflict some mild irritation, and therefore using gloves are recommended to avoid any accidents from the spines. Also, the Rainbow Pincushion Urchin can act as a good water quality indicator, because it drops its spines if the water quality is not appropriate. It is not advisable to keep the Urchins along with puffer and trigger fishes as they can pick the spine off them and can break open their shell to eat them. But the Rainbow Pincushion Urchin does well within a reef tank and can act as a method to wipe out algae problems. It doesn?t have any distinctive characteristic of female and male, thus breeding is quite impossible in captivity.