Ключевые слова: age, ammonite, ancient, antique, archeology, artifact, background, biology, bowl, cephalopod, circle, civilization, cliff, cockleshell, coil, epoch, era, evolution, fossil, fossilized, geological, geology, history, marine, mineral, mollusk, nacre, nacreous, natural, nature, ocean, old, organism, paleontology, patience, period, petrified, prehistoric, prehistory, primitive, rock, scientific, sea, seashell, shell, snail, spiral, stone, texture,