background fungus gap lichen lichens microorganism microorganisms mycobiont nature organism photobiont phycobiont rock rocks saavem symbiotic texture bush bushes christmas christmas rites herbal medicine herbs kiss mistletoe mistletoes plant sky symbiont symbiosis symbiote tradition tree trees birch spring african alert biological-interaction bird black broad-mouthed collagen creases curious eating endangered flat-mouthed folds food gray grazer grey heavy herbivore herbivorous hide horns inquisitive keratin large mammal Myna myna-birds mynah Noisy placid plumage powerful precocious rhino rhinoceros skin snout square-lipped-rhinoceros strong threatened tough watchful white-rhinoceros wide-lipped-rhinoceros wrinkled wrinkles