background dead death decay decompose decomposition ecology green leaf leaf skeleton natural nature recycle recycling Remains rot skeleton texture vein veins delicate dry gum leaves life old artifact closeup intricate plant plants shape Soil structure structures symmetric textures tree twig wheathered wheathered leaf wood autumn black bush dying fall park rest transparent white ancient arthropod cambrian eolith evolution extinct fossil impression marine neolith paleolith period petrifaction reconstruction relic specimen St trace trilobite