arms bumps echinoderms endoskeletons five five arms outer shell pitted rough sea sea creatures sea stars shapes skeleton starfish surface textures tube feet brown burr Castanea chestnut chinkapin chinquapin Fagaceae fruit green grove inner marron nature outer quill quills saavem sativa shell skin sweet texture tree colors colours consume display displayed dried edible food for sale medicinal medicine ready for purchase selection textured alive animal aquarium aquatic biology coast coastal coastline conservation coral creature environment environmental fish five-arms life marine ocean outer-shell pool rock rockpool sand save sea-creatures seashore seastar star tide tidepool tube-feet underwater water wild wildlife