They traversed the rest of the lightless cavern without incident, this time Robin keeping his flashlight switching on and off regularly, long enough to sweep the moonscape sufficiently to gain warnings of future assaults. Once they saw the ball-like bulk of a Moonbowler, as Robin mentally named it, in the distance, and they both carefully stopped and held their breath until it rolled away. At the far wall, Korree searched the various breaks until he found the one through which he had originally come. They passed through another lightless cavern, this one less of a desert than the other, where giant mushrooms towered like great trees in the darkness and where little chittering Moonmice ran about their feet, tiny green lights sparkling. The next cavern was a lighted one and this was now almost familiar to them. Beyond that was another lighted one through which a channel of water flowed only to disappear into a tiny crack in the far wall. This water, however, was yellowish and evil-smelling and made the entire cavern malodorous. Yet it too had its quota of strange vegetation. A series of rather small bubbles, not more than a couple of dozen yards across, came next, and then they arrived at a wide, deep one. The spot in the wall which let out on it was near the roof of this bubble, and they made their way delicately along a series of faults and ledges. Looking down, Robin could see that a lake of some bubbling oily substance filled the lower level of the bubble. Along one side, tucked in a corner near a tunnel opening, many hundreds of feet down, he spotted something odd. He stopped. Korree turned back, made his way along the narrow ledge and looked down to where he pointed. There was a small cleared space just before the opening, and there were several objects too far away to be seen clearly, but they looked for all the world like some sort of eggs. As they watched, Robin saw what seemed a shadowy figure move near one. Because of the curious glassy skins, that was probably an animal. Robin softly asked Korree what it was. "Is Glassie like Korree," answered Korree quietly. "A friend? One of your people? And what are they doing there?" asked Robin. Korree shook his head violently. "Not Korree people. That one is from down place. Is mighty people from...." He pointed downward to the Moon's core. "They come here to take...." He pointed now at the curious chemical lake. "They bring back down with them," he finished. Robin gasped. Here was evidence of his reasoning. The Glassies that lived near the core of the Moon were higher in civilization. Here evidently was a place where something usable could be gathered--the fluid of that lake. Possibly it might be fuel for burning, or substance usable as tar or cement. The beings down below came up for it, put it in tanks--the egg-shaped objects--and brought it back to their greater caverns.