Monster Life Starting from Picking Up Materials

When you see a male fire dragon flying over the sky, you cannot assert that it is a male fire dragon, because it may be a rare silver fire dragon before you see it. When you suspect that it was a silver fire dragon before, it may be a thorny dragon a long time ago. When you know from other populations that it was a thorny dragon a long time ago, you still cannot assert that it is a thorny dragon, because it is possible that it is a extinct dragon before others see it. You can almost be sure that it is a flying dragon, but you still cannot assert that it is a flying dragon, because it may be an old mountain dragon under the ground you cannot see. What is it? At the beginning, it was a hair spider.