Placing his eyes on the crystal, Duan Yu looked out of it, and saw the clear green water was moving gently, with no bounds, in which aquatic animals were swimming leisurely.

双眼贴着水晶向外瞧去，只见碧绿水流不住晃动，鱼虾水族来回游动，极目所至，竟无尽处。

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So the cave was underwater, Duan Yu realized, and the people having built it must have devoted a great deal of effort to let in the light using the big crystal, which was a really rare treasure.

他恍然大悟，原来处身之地竟在水底，当年建造石室之人花了偌大的心力，将外面的水光引了进来，这块大水晶更是极难得的宝物。

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Then he reached both hands to grope, and touched about ten bowl-big doornails. "It is really weird if some persons live here! "Duan Yu thought with a heart full of surprise and pleasure.

既有门环，必有大门，他双手摸索，当即摸到十余枚碗大的门钉，心中惊喜交集：“这门里倘若住得有人，那可奇怪之极了。”

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