barnacle bur color flower green plant pointed sharp sharp-pointed sky spike thistle thorn tip yellow Australian bird black-winged blue-black carnivore carnivorous crest crested egretta-picata Heron long-legged pied-egret Pied-Heron pond reeds reedy reflections sharp-beaked sharp-bill sharp-eyed thin wader wading wading-bird water yellow-bill yellow-legged aggressive alert common gymnorhina tibicen insectivore lookout Magpie protective sharp eyed swoop swooping territorial watchful watching Bin caution contain container containment contaminated contamination danger dangerous disposable disposal hospital hospital-objects infectious medical needles sanitation sharps special substances syringes used angles black and white buildings city corners glass high rise linear modern sharp corners Singapore straight up and down walls windows abstract angled appearance architectural architecture building contemporary contrast contrasting distinctive edged edges elements exterior external framed frames geometric geometric-shapes gray grey height high high-rise light lines patterned patterns perspectives sharp-cornered sharp-corners straight-up-and-down surface surfaces textured textures views wall