The Kandar Lithoglyph is a deeply unusual data repository of which only six copies are known to exist. Although "copies" may be the wrong term, due to the nature of the lithoglyph.
Each lithoglyph is a sizeable sphere, about five meters in diameter. It constantly emits ever-changing symbols from its surface. While the symbols exist in three dimensional space, the lithoglyph uses hypercausality flicker to force life forms to perceive them in many more dimensions simultaneously. The number of dimensions is always four or five higher than the life form evolved to perceive, which causes severe distress but rarely any permanent harm.
Since the causality flicker ruins any attempt to record the symbols, interpreting them is always a real-time event. It is clear that the some of the symbols relate to causality breaches caused during the ascension of several elder species, so it is possible that all the glyphs relate to causality errors, either past or upcoming.
Five of the lithoglyphs were discovered in regions with severe causality disturbances, including two dimensional rifts, two closed time loops, and a recursive wormhole. The sixth was discovered on Bau, thought to have been carried along from a causality-impaired homeworld.
At this time, it is thought that the lithoglyphs are literally scars from the universe ripping and folding over itself. Their highly unusual surface material seems to be evidence of that, as it is not technically made of matter.
Many sociologists believe - without much evidence - that the symbols recount the complete history of every species to have ever ascended. This has led to a surprising number of wars.
Many physicists believe - without much evidence - that the symbols monitor reality at a level that bypasses the Theory of Physical Undecidability. This has led to no wars, but four recorded planet-shatterings.
These objects are certainly worthy of being called priceless, but the problem is that some people consider them rather more than priceless. People and even whole species have become obsessed with obtaining or deciphering the Kandar Lithoglyphs, leading to astonishing wars, planet-tombs, and one particularly spectacular misadventure when the Ukal dropped one into their sun and an elder species of sociologists known as The Eternal Reminders blew up their sun to reclaim it.
Even if the lithoglyphs do contain the history of every ascended species, the number of species that have gone extinct because of their presence is far greater. It is a substantial concern, and many of the international treaties between starfaring species relate to access to oddities such as these lithoglyphs.
When a new lithoglyph was discovered on Bau, a sudden shockwave passed through interstellar politics. Rather than allow interstellar war to rip across the Bottlenose Nebula, it was decided that Bau's lithoglyph would not be studied until the natives join us as a superluminal civilization.
What we've learned about the Bauistas since then makes that decision Hilarious In Hindsight.