animal echinoderm Echinoidea empty green knob marine organism pattern protect rough sea shell urchin arms bumps echinoderms endoskeletons five five arms outer shell pitted sea creatures sea stars shapes skeleton starfish surface textures tube feet Asteroidea background beauty design detail marine animals mollusks Protoreaster red Red-knobbed sea animal sea-star seashell star white brown colors colours consume display displayed dried edible food for sale medicinal medicine ready for purchase selection textured alive aquarium aquatic biology coast coastal coastline conservation coral creature environment environmental fish five-arms life nature ocean outer-shell pool rock rockpool sand save sea-creatures seashore seastar tide tidepool tube-feet underwater water wild wildlife appearance balate brine bêche-de-mer elongated fish market harvested holothurian home cooking human consumption leathery market rubbery scavengers sea cucumbers sea food shopping Sizes skin slimy slippery smell tough trepang variations varieties wet wet market worm-like