The Pincushion Urchin is round with very short spines and grows only up to 3 inches in diameter. It may carry shells, algae, bits of rubble on its back in order to shade or camouflage itself. The 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, so that the live rocks encourage the growth of algae on itself. The Pincushion Urchin is not really considered reef safe, as it may damage or nip over the delicate corals by crawling over it. It can also fed by introducing attached algae sheets to a piece of rock with a clip or rubber band, if there is deficient in algal growth in the aquarium. Apart from this, the Pincushion Urchin can also be provided with dried seaweed for its continued good health. If its spines are poked in your hand while handling, it may cause some mild irritation, and therefore using gloves are recommended to avoid any accidents from the spines. Also, the Pincushion Urchin can act as a good water quality indicator, because it drops its spines if the water quality is not of a good quality level. 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 Pincushion Urchin does well within a reef tank and can act as a method to wipe out a large algae problem. It doesn?t have any distinctive characteristic of female and male, thus breeding is quite impossible in captivity.
The Pincushion Urchin is a small Urchin that is white and green in color with very sharp protruding spines -- like pins. In Nature, these spines serve as an excellent defense mechanism from predators. These Urchins are nocturnal and do most of their grazing at night. During the day they will usually stay stationary on the aquarium glass, or in hiding spots in rockwork. All Urchins like lots of rockwork that they can crawl and feed on. They are excellent algae eaters.Urchins belong to a Class known as Echinoidea, which consists of creatures that have a skeleton made of ten plates covered with spines. Urchins have mostly round bodies with protective spines on their upperside and tubular feet and a mouth on the underside. Artistotle once wrote of the five parts of the Urchin's mouth: "In reality the mouth-apparatus of the urchin is continuous from one end to the other, but to outward appearance it is not so, but looks like a horn lantern with the panes of horn left out." This holds true today as the mouth of the Urchin is referred to as "Aristotle's Lantern". The mouth of the Urchin is used to scrape algae from rockwork. The spines of the Urchin are a defense mechanism that are barbed like that of a fish hook and can inflict serious pain to the predator. These spines can either come to a sharp point or can be stubby and blunt.