Well, now let's have a little "Wild Speculation" here as to what that "thing" could be. I've got a couple ideas. Anybody else???
* Scanner - detects and analyzes anyone entering the cave.
* Portal - hmmmmm...to where?
* Force field generator - to protect the cave in emergency situation.
* Transmitter / Communicator - warn intruders, transmit to space
* Hologram generator - similar to an artifical rock surface with glyph we've seen somplace else. Perhaps probes don't "see" holograms.
Look at what Andrew has to say today about "metal/not metal" that adds some fuel to this discussion.
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Zero
0=o