FINALLY, thanks to the hint from R.P. Corse, I looked again at the dead body in the Hall of Minds. In the closeup of the dead body I found a HAMMER (just above the middle of the body). I then went back to the Landscape, went to the "stone fortress" (seen when you face the telescope in closeup, and then turn left), and used the HAMMER on the box, was now able to open the box, and take the "MAGNETIC ROCK". I went back to the Ancient Life Room, placed the SAP COVERED WATERSTONE into the "furnace", then used the MAGNETIC ROCK on the PANEL'S LOCK and it opened. The rest (finale) is in your walkthrough.
I suggest, if you ARE going to amend your walkthrough, that the HAMMER be picked up when you first look at the DEAD BODY. It saves a lot of "leg-work", in my not so humble opinion

Thanks to all of you for getting me through this short but FUN game. I'm sure that "I'll be baaaaack".