The ruby brittle star (Ophioderma rubicundum) is a species of brittle star. It is commonly found on the outer edges of coral reefs in the Caribbean Sea at depths of up to 80 feet (25 meters). Like all brittle stars, it has a central disk with long, flexible arms. This species is red in color with cream colored bands along its arms. Instead of spines, the arms are covered with scales for protection. The ruby brittle star can grow to a maximum size of 21 inches (55 centimeters) in diameter. It is nocturnal and forages for food at night.