anatomy biology bones diagram education medicine science skeletal skeleton skeletons study autumn bare bare branches branches directional empty extensive fall large spreading tangled tree tree top turned twisted windswept artificial bone display halloween life-like life-sized make-believe medical-model model models plastic scary skull skulls blue claw-like pale blue sky above background bare-branches budding buds clouds contrast contrasting deciduous reaching-up silhouette spread spring stark straggly tall tips tree-top trees anatomical carved dirty discolored discoloured misshapen out-of-shape partial plaster replica scraped shape shaped