Black Friday: lifetime access is on a special offer in the app, until November 30. Black Friday: special offer on lifetime access, until November 30. Download
석화는 고대 식물의 화석을 만드는 과정입니다.seokhwa-neun gode sigmul-ui hwasogeul mandeulneun gwajeong-imnida.Petrifaction is the process that creates fossils of ancient plants.