Here is an article about several accounts of perpetual lamps found in toumbs, written in the late-19th century by a Theosophist and Freemason:
http://www.levity.com/alchemy/westcott.html
Wow, that was intriguing. Did not know how coveted this discovery was, and not surprised.
While reading this, the initial thought I had was of an anecdote I heard from Emery Smith about his ufo crash investigation that led him to the Vatican’s secret Archives. I know it sounds dubious to many, let alone the fact that ES could have visited this place. But lets put that aside for a moment.
One thing he did mention was exactly that, a lamp on the walls of the corridors connecting to the vast, state-of-the-art library.
He said it looked like a Tibetan object which name escapes me (I was able to recover the picture below). Now unfortunately I can’t remember if this was a case, where no shadows were to be found. But I’ve definitely heard of this phenomenon elsewhere (David Adair’s Area 51 DUMB anecdote) and its fascinating just to wonder about it!
All in all, it sounds like it fits the general description of a coveted, mysterious object that was known to a few, back in the days.
By the way, the last story in the link of the hidden, burried door with a figurine that moves to protect the crypt is e.p.i.c.
PS: the episode, if anyone can find it, is called Vatican Secret Tech, Cosmic Disclosure penultimate season.
PPS: I also remember seeing this exact figurine at a Tibetan shop selling singing bowls. So it’s a well-known artifact. Now whether it was used a perpetual lamp is a different story altogether..