crustosea. 長成外殼狀的、緊貼在土壤(岩石)的學術名詞殼狀的：動物學皮殼狀的：礦物學平伏密著於表面上的：植物學英文釋義(of lichens) having a thin crusty thallus that adheres closely to the surface on which it is growing