Mediterranean feather star (Lat. Antedon mediterranea). It is found at depths down to about 80 metres (260 ft) and favours areas with strong currents which bring plenty of food within reach. It is found on rocky or sandy seabeds rich in algae including encrusting algae, or among sea grasses (Posidonia oceanica). It has a vestigial stalk, the base of which bears up to forty grasping cirri, articulated prehensile structures with which it can cling to a hard surface. The arms can be rolled up if danger threatens, but when they are extended to feed, they are about 10 cm (4 in) long. They are fragile but if one gets broken off, the animal can regenerate it. The colour of this crinoid is quite variable and ranges from white, yellow, orange or red to brown and dark purple, sometimes with bands of contrasting colour. It hides during the day in concealed locations emerging at night into more exposed areas. It feeds by filtering out plankton and other small particles from the passing sea water.